Optical pickup device and optical disk drive

ABSTRACT

To reduce the size or thickness of an optical pickup device and an optical disk drive, an optical pickup device includes a light source that radiates laser light; a condensing member that condenses the laser light onto a recording medium; an optical member that reflects some of the laser light radiated from the light source into the condensing member and transmits the rest of the radiated laser light; and a light receiving sensor that receives the rest of the laser light transmitted through the optical member so as to detect an amount of laser light.

BACKGROUND

1. Field of the Invention

The present invention relates to an optical disk drive, which can bemounted on portable electronic apparatuses such as notebook computers orelectronic apparatuses such as stationary personal computers, and to anoptical pickup device which can be mounted on the optical disk drive.

2. Description of the Related Art

Recently, demands for optical disk drives that can record or reproduceinformation on an optical disk by using short-wavelength laser such asblue laser, in addition to CD or DVD by using infrared laser or redlaser have been increased. (For example, refer to JP-A-11-86328)

In JP-A-11-86328, however, semiconductor laser is disposed under anobject lens. Therefore, the device increases in size.

SUMMARY

An optical pickup device according to an aspect of the present inventionincludes a light source that radiates laser light; a condensing memberthat condenses the laser light onto a recording medium; an opticalmember that reflects some of the laser light radiated from the lightsource into the condensing member and transmits the rest of the radiatedlaser light; and a light receiving sensor that receives the rest of thelaser light transmitted through the optical member so as to detect anamount of laser light.

According to the above aspect of the present invention, the opticalpickup device can be reduced in size and thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing an optical pickup device according toan embodiment of the present invention.

FIG. 2 is a diagram showing the optical pickup device according to theembodiment of the invention.

FIG. 3 is a diagram showing a module on which the optical pickup deviceaccording to the embodiment of the invention is mounted.

FIG. 4 is a diagram showing a module on which the optical pickup deviceaccording to the embodiment of the invention is mounted.

FIG. 5 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 6 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 7 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 8 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 9 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 10 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 11 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 12 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 13 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 14 is a diagram showing light which is emitted from a light sourceof the optical pickup device according to the embodiment of theinvention.

FIG. 15 is a diagram showing light which is emitted from the lightsource of the optical pickup device according to the embodiment of theinvention.

FIG. 16 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 17 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 18 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 19 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 20 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 21 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 22 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 23 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 24 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 25 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 26 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 27 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 28 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 29 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 30 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 31 is a diagram showing the temperature distribution of the opticalpickup device according to the embodiment of the invention.

FIG. 32 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 33 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 34 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 35 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 36 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 37 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 38 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 39 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 40 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 41 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 42 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 43 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 44 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 45 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 46 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 47 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 48 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 49 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 50 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 51 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 52 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 53 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 54 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 55 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 56 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 57 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 58 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 59 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 60 is a diagram showing an optical disk drive according to anembodiment of the invention.

FIG. 61 is a diagram showing a portion of the optical disk driveaccording to the embodiment of the invention.

FIG. 62 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 63 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 64 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 65 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 66 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 67 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 68 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 69 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 70 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 71 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 72 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 73 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 74 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

FIG. 75 is a diagram showing a portion of the optical pickup deviceaccording to the embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 is a schematic view illustrating the construction of an opticalpickup device according to an embodiment of the present invention. TheA-side of FIG. 1 from a short wavelength optical unit 1 and a longwavelength optical unit 3 to a collimator lens 8 by reference to adouble wavy line is a schematic view when the optical pickup device isseen from a Z-direction (the top side of the page) in FIG. 2. The B-sideof FIG. 1 from a inclined-right mirror 9 to an optical disk 2 byreference to the double wavy line is a schematic view when the opticalpickup device is seen from an R-direction in FIG. 2.

In FIG. 1, reference numeral 1 represents a short wavelength opticalunit which emits short-wavelength laser. The short wavelength opticalunit 1 emits light with a wavelength of 400 to 415 nm. In thisembodiment, the short wavelength optical unit 1 is constructed so as toemit light with a wavelength of 405 nm. In general, light with theabove-described laser wavelength has a blue color to violet color. Inthis embodiment, although the detail of the short wavelength opticalunit 1 will be described below, the short wavelength optical unit 1includes a light source section 1 a which emits short-wavelength laser,a light receiving section 1 b for detecting a signal which receiveslight reflected from the optical disk 2, a light receiving section 1 cwhich is provided so as to monitor an amount of light emitted from thelight source section 1 a, an optical member 1 d, and a holding member(not shown) which holds the above-described constituent members in apredetermined positional relationship. The light source member 1 a isprovided with a semiconductor laser element (not shown) which consistsprimarily of GaN. The light emitted from the semiconductor laser elementis incident on the optical member 1 d, and some of the incident light isreflected by the optical member 1 d so as to enter the light receivingsection 1 c. Although not shown, the light receiving section 1 c isprovided with a circuit which converts light into an electrical signaland adjusts the intensity of light to a desired level, the light beingemitted from the light source section 1 a based on the electricalsignal. Further, most of light emitted from the light source section 1 ais introduced toward the optical disk 2 through the optical member 1 d,and the light reflected from the optical disk 2 is incident on the lightreceiving section 1 b through the optical member 1 d. The lightreceiving section 1 b converts light into an electrical signal andgenerates an RF signal, a tracking error signal, a focus error signaland the like from the electrical signal. In the optical member 1 d, ahologram 1 e is provided to separate the reflected light from theoptical disk 2 such that a focus error signal can be obtained.

In this embodiment, one short wavelength optical unit including thelight source section 1 a, the light receiving sections 1 b and 1 c, andthe optical member 1 d is constructed so as to miniaturize the opticalpickup device. However, at least one of the receiving sections 1 b and 1c may be removed from the short wavelength optical unit 1 so as to beseparately constructed. Alternately, the optical member 1 d may beremoved from the short wavelength optical unit 1 so as to be separatelyconstructed.

Reference numeral 3 represents a long wavelength optical unit whichemits laser with a long wavelength. The long wavelength optical unit 3emitting light with a wavelength of 640 to 800 nm is constructed so asto emit light with one kind of wavelength or a plurality of lights withplural kinds of wavelengths. In this embodiment, the long wavelengthoptical unit 3 is constructed so as to emit a light flux with awavelength of about 660 nm (red: corresponding to DVD) and a light fluxwith a wavelength of about 780 nm (infrared: corresponding to CD). Inthis embodiment, although the details of the long wavelength opticalunit 3 will be described below, the long wavelength optical unit 3includes a light source section 3 a which emits laser with a longwavelength, a light receiving section 3 b for detecting a signal whichreceives light reflected from the optical disk 2, a light receivingsection 3 c which is provided so as to monitor an amount of lightemitted from the light source section 3 a, an optical member 3 d, aholding member (not shown) which holds those constituent members in apredetermined positional relationship. The light source section 3 a isprovided with a semiconductor laser element (not shown). Thesemiconductor laser element is composed of a mono block (monolithicstructure). The semiconductor layer element emits a light flux with awavelength of about 660 nm (red) and a light flux with a wavelength ofabout 780 nm (infrared) from the mono-block element. In this embodiment,the mono-block element emits two light fluxes. However, two elements maybe built therein, each element emitting one light flux. A plurality oflight fluxes emitted from the semiconductor layer element are incidenton the optical member 3 d, and some of the incident light is reflectedby the optical member 3 d so as to enter the light receiving section 3c. Although not shown, the light receiving section 3 c is provided witha circuit which converts light into an electrical signal and adjusts theintensity of light to a desired level, the light being emitted from thelight source section 3 a based on the electrical signal. Further, mostof light emitted from the light source section 3 a is introduced towardthe optical disk 2 through the optical member 3 d, and the lightreflected from the optical disk 2 is incident on the light receivingsection 3 b through the optical member 3 d. The light receiving section3 b converts light into an electrical signal and generates an RF signal,a tracking error signal, a focus error signal and the like from theelectrical signal. In order to generate a focus error signal for CD, theoptical member 3 d is provided with a hologram 3 e which separatesreflected light from the optical disk 2 into a plurality of lights suchthat the respective lights are guided to predetermined places of thelight receiving section 3 b.

In this embodiment, one long wavelength optical unit including the lightsource section 3 a, the light receiving sections 3 b and 3 c, and theoptical member 3 d is constructed so as to miniaturize the opticalpickup device. However, at least one of the receiving sections 3 b and 3c may be removed from the long wavelength optical unit 3 so as to beseparately constructed. Alternately, the optical member 3 d may beremoved from the long wavelength optical unit 3 so as to be separatelyconstructed.

Reference numeral 4 represents a beam shaping lens, through which lightemitted from the short wavelength optical unit 1 and reflected lightfrom the optical disk 2 pass. Preferably, the beam shaping lens 4 isformed of glass which is hardly degraded by the passing ofshort-wavelength laser. In this embodiment, although the beam shapinglens 4 is formed of glass, the beam shaping lens 4 may be formed ofanother material as long as the material is hardly degraded by thepassing of short-wavelength laser. The beam shaping lens 4 is providedso as to remove astigmatism of short-wavelength laser and astigmatismoccurring in a light path from the short wavelength optical unit 1 tothe optical disk 2. For purpose of the beam shaping lens 4, the lightreflected from the optical disk 2 may be caused to be incident on theshort wavelength optical unit 1 without the beam shaping lens 4. In thisembodiment, however, the reflected light from the optical disk 2 iscaused to be incident on the short wavelength optical unit 1 through thebeam shaping lens 4. Further, in this embodiment, although the beamshaping lens 4 is used so as to reduce astigmatism of light with a shortwavelength, a beam shaping prism or beam shaping hologram may be usedinstead.

In both ends of the beam shaping lens 4, a convex portion 4 a and aconcave portion 4 b are respectively provided. The beam shaping lens 4is disposed so that the light emitted from the short wavelength opticalunit 1 is first incident on the convex portion 4 a so as to be emittedfrom the concave portion 4 b.

Reference numeral 5 represents an optical part. The optical part 5 isdisposed ahead of the beam shaping lens 4 on the light path and in theside of the concave section 4 b of the beam shaping lens 4. That is, thelight emitted from the short wavelength optical unit 1 is incident onthe optical part 5 through the beam shaping lens 4 so as to be guided tothe optical disk 2, and the light reflected from the optical disk 2 isincident on the short wavelength optical unit 1 after sequentiallypassing through the optical part 5 and the beam shaping lens 4. Theoptical part 5 is provided with a hologram or the like, which has atleast the following function. That is, the function is to separate thelight reflected from the optical disk 2 into predetermined light fluxesso as to mainly generate a tracking error signal. As described above,the light is separated into a plurality of light fluxes by the hologram1 e provided in the optical member 1 d, in order to generate a focuserror signal. Further, the light is separated into a plurality of lightfluxes by the optical part 5, in order to generate a tracking errorsignal.

Although the details will be described below, the optical parts 5 mayhave a function of serving as a RIM intensity correction filter whichattenuates the light intensity of short-wavelength light at thesubstantial center portion. Further, the optical parts 5 may beseparated into two optical parts. One of the optical parts 5 can serveto separate the light reflected from the optical disk 2 intopredetermined light fluxes so as to mainly generate a tracking errorsignal, and the other of the optical parts 5 can serve as a RIMintensity correction filter.

Reference numeral 6 represents a relay lens though which long-wavelengthlight emitted from the long wavelength optical unit 3 passes. The relaylens 6 is formed of a transparent member such as resin or glass. Therelay lens 6 is provided so as to effectively guide light emitted fromthe long wavelength optical unit 3 into a backward member. Further, withthe relay lens 6 being provided, the long wavelength optical unit 3 canbe disposed toward a beam splitter 7, which makes it possible to realizethe miniaturization of device.

Reference numeral 7 represents a beam splitter. In the beam splitter 7,at least two transparent members 7 b and 7 c are provided so as to bebonded to each other. Between the transparent members 7 b and 7 c, oneinclined surface 7 a is provided on which a wavelength selecting film isformed. As the wavelength selecting film is directly formed on theinclined surface 7 a of the transparent member 7 c into which the lightemitted from the short wavelength optical unit 1 enters, the transparentmember 7 b is bonded to the inclined surface 7 a of the transparentmember 7 c, on which the wavelength selecting film is formed, through abonding material such as resin or glass.

Further, the beam splitter 7 has a function of reflecting theshort-wavelength light emitted from the short wavelength optical unit 1and transmitting the light emitted from the long wavelength optical unit3. That is, the light emitted from the short wavelength optical unit 1and the light emitted from the long wavelength optical unit 3 are guidedin the substantially same direction.

Reference numeral 8 represents a collimator lens which is movably held.The collimator lens 8 is attached to a slider 8 b, and the slider 8 b ismovably attached to a pair of support members 8 a which are providedsubstantially parallel to each other. A lead screw 8 c provided with ahelical groove is provided substantially parallel to the support member8 a, and a projection inserted into the groove of the lead screw 8 c isprovided on the end portion of the slider 8 b. The lead screw 8 c iscoupled to a gear group 8 d which is provided with a driving member 8 e.A driving force of the driving member 8 e is transmitted to the leadscrew 8 c through the gear group 8 d, and the lead screw 8 c is rotatedby the driving force. As a result, the slider 8 b moves along thesupport member 8 a. That is, the collimator lens 8 can be moved in adirection approaching or departing from the beam splitter 7 by adifference in driving direction or driving speed of driving member 8 e.Further, the speed of the movement can be adjusted.

As the driving member 8 e, various motors are used, among which astepping motor is preferably used. An amount of rotation of the leadscrew 8 c is determined by adjusting the number of pulses to be sent tothe stepping motor. As a result, it is possible to easily set an amountof movement of the collimator lens 8.

As such, as the collimator lens 8 is constructed so as to approach ordepart from the beam splitter 7, it is possible to easily adjust aspherical aberration. That is, the spherical aberration ofshort-wavelength light can be adjusted by the position of the collimatorlens 8. Therefore, at least any one of recording and reproducing can beeffectively performed on a first recording layer provided in the opticaldisk, the first recording layer corresponding to a short wavelength, anda second recoding layer provided at a depth different from the firstrecording layer, respectively.

Through the collimator lens 8, long-wavelength and short-wavelengthlights incident from the beam splitter 7 pass. Therefore, the collimatorlens 8 is formed of glass or, preferably,short-wavelength-light-resistant resin (which is not or hardly degradedby short-wavelength light). The collimator lens 8 transmitsshort-wavelength or long-wavelength light reflected by the optical disk2.

In this embodiment, the collimator lens 8 is moved by the driving member8 e in order to correct a spherical aberration of short-wavelengthlight. However, the collimator lens 8 may be moved by anotherconstituent member. Further, the spherical aberration ofshort-wavelength light may be adjusted by another unit.

Reference numeral 9 represents a inclined-right mirror. Theinclined-right mirror 9 is provided with a quarter wavelength member 9 aacting on short-wavelength light. As the quarter wavelength member 9 a,a quarter wavelength member is preferably used, which can rotate apolarization direction of light at about 90 degrees, the light havingpassed two times (through an outward path and inward path). In thisembodiment, the quarter wavelength member 9 a is interposed inside theinclined-right mirror 9. On the surface of the inclined-right mirror 9,on which the light emitted from each of the units 1 and 3 is incident, awavelength selecting film 9 b is provided, which has a function ofreflecting most of long-wavelength light emitted from the longwavelength optical unit 3 and transmitting most of short-wavelengthlight emitted from the short wavelength optical unit 1.

Reference numeral 10 represents an object lens for long-wavelengthlaser. The object lens 10 condenses light reflected from theinclined-right mirror 9 on the optical disk 2. Although the object lens10 is used in this embodiment, other condensing members such as ahologram and the like may be used. Further, it is natural that the lightreflected from the optical disk 2 passes through the object lens 10. Theobject lens 10 is formed of glass or resin.

Reference numeral 11 represents an optical part. The optical part 11 isan optical part provided between the object lens 10 and theinclined-right mirror 9. The optical part 11 includes an aperture filterfor implementing a required number of apertures which can correspond toa DVD optical disk (light with a wavelength of about 660 nm) and a CDoptical disk (light with a wavelength of about 780 nm); a polarizationhologram responding to light with a wavelength of about 660 nm; and aquarter wavelength member (preferably, a quarter wavelength plate). Theoptical part 11 is composed of a dielectric multilayer, a diffractiongrating aperture unit or the like. The polarization hologram addspolarized light to light with a wavelength of about 660 nm (light with awavelength of about 660 nm is separated into light for tracking errorsignal or focus error signal). Further, the quarter wavelength memberrotates the polarization direction of an inward path of light with awavelength of about 660 nm or 780 nm with respect to an outward paththereof, by 90 degrees.

Reference numeral 12 represents a inclined-right mirror which reflectsmost of short-wavelength light. The inclined-right mirror 12 is providedwith a reflective film.

Reference numeral 13 represents an object lens. The object lens 13condenses light reflected from the inclined-right mirror 12 on theoptical disk 2. Although the object lens 13 is used in this embodiment,other condensing members such as a hologram and the like may be used.Further, it is natural that the light reflected from the optical disk 2passes through the object lens 13. The object lens 13 is formed of glassor resin. In this case, when the object lens 13 is formed of resin, itis preferable that the object lens 13 is formed ofshort-wavelength-light-resistant resin (which is not or hardly degradedby short wavelength light).

Reference numeral 14 represents an achromatic diffraction lens providedbetween the object lens 13 and the inclined-right mirror 12. Theachromatic diffraction lens 14 has a function of correcting a chromaticaberration. The achromatic diffraction lens 14 is provided so as toreduce a chromatic aberration occurring in each optical part throughwhich short-wavelength light passes. Basically, the achromaticdiffraction lens 14 is constructed by forming a desired hologram on alens, and the correction degree of chromatic aberration can bedetermined by adjusting at least one of a grating pitch of the hologramand the curvature radius of the lens. The achromatic lens 14 is formedof resin such as plastic or glass. When resin is used, it is preferablethat the achromatic lens 14 is formed ofshort-wavelength-light-resistant resin (which is not or hardly degradedby short wavelength light).

The specific disposition of the optical system constructed in such amanner will be described with reference to FIG. 2.

FIG. 2 illustrates an example where the optical construction shown inFIG. 1 is embodied. Although members thereof have a slightly differentshape from the respective members shown in FIG. 1, functions thereof arethe substantially same.

Reference numeral 15 represent a base. On the base 15, theabove-described respective members are fixed or movably attached. Thebase 15 is formed of metal or metallic alloy, such as zinc, a zincalloy, aluminum, an aluminum alloy, titanium, a titanium alloy or thelike. Preferably, the base 15 is manufactured using a die casting methodin terms of mass production. The base 15 is movably held by a pickupmodule shown in FIGS. 3 and 4.

Reference numeral 20 represents a frame. In FIGS. 3 and 4, the frame 20has shafts 21 and 22 disposed in parallel to each other. The base 15 ismovably attached to the shafts 21 and 22. Further, in the side of theshaft 22 opposite to the shaft 21, a screw shaft 23 provided with ahelical groove is attached substantially parallel to the shafts 21 and22 so as to freely rotate around the frame 20. Although not shown indetail, a member provided integrally with or separately from the base 15is geared into the groove provided on the screw shaft 23. The screwshaft 23 is geared with a gear group 24 a which is rotatably provided inthe frame 20, and the gear group 24 a is geared with a feed motor 24.Accordingly, when the feed motor 24 rotates, the gear group 24 arotates. In accordance with the rotation, the screw shaft 23 is rotated.As the screw shaft 23 is rotated, the base 15 can reciprocate in anarrow direction shown in FIG. 3. At this time, the feed motor 24 isdisposed substantially parallel to the screw shaft 23. Further, theframe 20 has the optical disk 2 mounted thereon, and a spindle motor 25for rotating the optical disk 2 is attached by such a technique as screwfastening or bonding.

Supplementarily, a control board 26 is provided separately from theframe 20, as shown in FIG. 3. The control board 26 and the base 15 areelectrically coupled through a flexible board 29, and the control board26 is also electrically connected to the spindle motor 25 by a memberwhich is not shown. The control board 26 is provided with a connector 27which performs electric connection with the control board provided inthe optical disk drive. A flexible board (not shown) or the like isplugged in the connector 27, thereby performing electrical connection.

As shown in FIG. 4, a frame cover 30 having a function of protectingmembers may be provided at least in the side of the frame 20 opposite tothe optical disk. The frame cover 30 is provided with a through-hole 31,from which at least the object lenses 10 and 13 are exposed in the base15 and the spindle motor 25 projects by a predetermined amount. Further,in FIGS. 3 and 4, the frame 20 is provided with an attachment section 20a for fixing the frame 20 to another member, and a screw or the like isinserted into the attachment section 20 a so as to attach the frame 20to another member.

In FIG. 2, the short wavelength optical unit 1, the long wavelengthoptical unit 3, the beam shaping lens 4, the optical part 5, the relaylens 6, the beam splitter 7, the support member 8 a, the lead screw 8 c,the gear group 8 d, the driving member 8 e, the inclined-right mirrors 9and 12 and the like are bonded to the base 15 by using an organicadhesive such as a light-curing adhesive or epoxy-based adhesive or ametallic adhesive such as solder or lead-free solder. Alternately, theyare attached to the base 15 by a technique such as screw fastening,fitting, pressing-in or the like.

The lead screw 8 c and the gear group 8 d are rotatably attached to thebase 15.

Reference numeral 17 represents a suspension holder. The suspensionholder 17 is attached to the base 15 by various bonding techniquesthrough a yoke member to be described below. The lens holder 16 and thesuspension holder 17 are coupled to each other through a plurality ofsuspensions 18. The lens holder 16 is supported so as to move in apredetermined range with respect to the base 15. The object lens 10 and13, the optical part 11, the achromatic diffraction lens 14 and the likeare attached to the lens holder 16. In accordance with the movement ofthe lens holder 16, the object lens 10 and 13, the optical part 11, theachromatic diffraction lens 14 and the like are moved together with thelens holder 16. As shown in FIG. 5, the inclined-right mirrors 9 and 12are attached to protuberating portions 15 d and 15 e, respectively, by alight-curing resin or instant adhesive, the protuberating portions 15 dand 15 e being provided so as to protuberate on the base 15. When theinclined-right mirror 9 is attached to the protuberating portion 15 d, abonding position between the inclined-right mirror 9 and theprotuberating portion 15 d is considered so as not to block lightpassing through the inclined-right mirror 9. Since the inclined-rightmirrors 9 and 12 are provided so as to be positioned under the lensholder 16, they are not shown in FIG. 2.

The inclined-right mirror 9 is provided to be inclined with respect tothe light flux which is emitted from the short wavelength optical unit 1so as to pass through the beam splitter 7 and the collimator lens 8.Therefore, the light flux coming from the short wavelength optical unit1 is refracted when passing through the inclined-right mirror 9. Then,the light flux moves in a direction away from the object lenses 10 and13 by a distance d shown in FIG. 5.

As shown in FIG. 5, the object lenses 10 and 13 are disposed in an orderof the object lens 10 and the object lens 13 along the direction wherelight emitted from the short wavelength optical unit 1 or longwavelength optical unit 3 so as to pass through the beam splitter 7 orthe collimator lens 8 proceeds. The thickness of the object lens 13 onthe lens axis is larger than that of the object lens 10. In other words,in the lens holder 16, the object lenses 10 and 13 are disposed in anorder of the object lens 13 and the object lens 10 from the side of thesuspension holder 17, as shown in FIG. 6.

As the object lenses 10 and 13 are disposed in such a manner, a lightflux is not blocked by the object lens 13 or the achromatic diffractionlens 14 even though the lens holder 16 is driven up and down. Therefore,it is possible to make the optical pickup device slim.

Referring to FIGS. 6 to 8, the construction around the lens holder 16will be described. FIG. 7 is a sectional view taken along A-A line ofFIG. 6 showing the optical pickup device according to this embodiment.

As shown in FIG. 7, the lens holder 16 is provided with through-holes 16a and 16 b. The object lenses 10 and 13 are brought down into thethrough-holes 16 a and 16 b, respectively, from a direction of an arrowP1 shown in FIG. 7 and are then fixed by a light-curing adhesive or thelike. At this time, the outer circumferences of the object lenses 10 and13 are abutted on the circumferential edges of the through-holes 16 and16 b of the lens holder 16, respectively. Further, the optical part 11and the achromatic lens 14 are inserted into the through-holes 16 a and16 b, respectively, from a direction of an arrow P2 shown in FIG. 7 andare also fixed by a light-curing adhesive or instant adhesive. At thistime, the outer circumferences of the optical part 11 and the achromaticdiffraction lens 14 are abutted on the circumferential edges of thethrough-holes 16 a and 16 b of the lens holder 16.

Reference numerals 33 and 34, respectively, represent a focus coil. Asshown in FIG. 6, the respective focus coils 33 and 34 are wound in asubstantial ring shape and are provided in diagonal positions of thelens holder 16. Reference numerals 35 and 36, respectively, represent atracking coil. The respective tracking coils 35 and 36 are also wound ina substantial ring shape and are provided in different diagonalpositions of the lens holder 16. Between the focus coils 33 and 34 andthe lens holder 16, sub-tracking coils 37 and 38 are respectivelyprovided. With the sub-tracking coils 37 and 38 being provided, it ispossible to suppress unnecessary inclination of the lens holderoccurring on tracking. The sub-tracking coils 37 and 38 are bonded tothe lens holder 16 by an organic adhesive such as a heat-curing adhesiveor the like. Then, the focus coils 33 and 34 may be bonded on thesub-tacking coils 37 and 38 by an adhesive or the like. Further, abonding body in which the sub-tracking coil 37 and the focus coil 33 arepreviously bonded may be bonded to the lens holder 16. Preferably, aheat-curing adhesive is used for bonding between the coils and the lensholder 16 or bonding between the coils. However, a light-curing adhesiveor other adhesives may be used for bonding. Further, if the coils andthe lens holder or the coils can be reliably disposed in predeterminedpositions, other methods may be used for bonding.

Three of the suspensions 18 are provided in each side of the lens holdersuch that the lens holder 16 is interposed therebetween. The suspensions18 elastically connect the suspension holder 17 and the lens holder 16.At least the lens holder 16 can be displaced in a predetermined rangewith respect to the suspension holder 17. In this embodiment, althoughthree of suspensions 18 are provided in one side (six in total), alarger number (for example, eight) of suspensions 18 may be provided, ora smaller number (for example, four) of suspensions 18 may be provided.For convenience, three of the suspensions 18 positioned in the upperside of FIG. 6 are respectively set to suspensions 18 a, 18 b, and 18 cfrom the side opposite to the optical disk 2, and three of thesuspensions 18 positioned in the lower side of FIG. 6 are respectivelyset to suspensions 18 d, 18 e, and 18 f from the side opposite to theoptical disk 2. Both ends of the suspension 18 are fixed to the lensholder 16 and the suspension holder 17, respectively, by insert molding.

Hereinafter, an example of wiring lines between the suspensions 18 andthe respective coils provided in the lens holder 16 will be described.That is, an electric current flows in the respective coils provided inthe lens holder 16 through the suspensions 18.

Both ends of the focus coil 33 are electrically connected to thesuspensions 18 a and 18 b, respectively, and both ends of the focus coil34 are electrically connected to the suspensions 18 d and 18 e,respectively. Further, the tracking coil 35, the sub-tracking coil 37,tracking coil 36, and the sub-tracking coil 38 are connected in series.One end of the coil group connected in series is connected to thesuspension 18 c, and the other end of the coil group is connected to thesuspension 18 f. The ends of the respective coils and the suspensions 18are electrically connected by a metallic bonding material such as solderor lead-free solder.

The suspensions 18 may be composed of wire of which the cross-section isformed in a substantially circular or elliptical shape or in a polygonalshape such as a rectangle. Further, a plate spring may be processed intothe suspension 18. The suspension 18 is formed in a reverse V-shape, ifit is seen from the light emission direction of the object lenses 10 and13 with the suspension holder 17 being set in the lower side. In thesuspension 18, tension is applied. Accordingly, it is possible to reducethe size and the resonance of the suspension 18 in a buckling direction.

Reference numeral 32 represents a yoke member formed of Fe or a Fealloy. If Fe or a Fe alloy is used, it is easy to construct a magneticcircuit. The yoke member 32 is integrally provided with upright portions32 a, 32 b, and 32 c facing the respective coils provided in the lensholder 16 by a cutting and raising process. Further, on the lowersurface of the yoke member 32, an opening portion 32 d is provided. Fromthe opening portion 32 d, the inclined-right mirrors 9 and 12 fixed tothe base 15 enter. Further, the suspension holder 17 is fixed on theyoke member 32 by a technique such as bonding, and the yoke member 32 isbonded to the base 15 by a technique such as bonding.

Reference numerals 39 to 42 are magnets provided on the yoke member 32by a technique such as bonding or the like.

The magnet 39 is attached to the upright portion 32 c and is provided soas to face the focus coil 33 and the sub-tracking coil 37. Further, themagnet 39 is disposed in the yoke member 32 and is magnetized so that amagnetic pole thereof is exposed on the surface facing the focus coil 33and the sub-tracking coil 37 in an order of the S pole and the N pole inthe height direction of FIG. 7 from the bottom surface toward the objectlenses 10 and 13.

The magnet 40 is attached in the side opposite to the side, where themagnet 39 of the upright portion 32 c is attached, in the widthdirection shown in FIG. 6. Further, the magnet 40 is provided so as toface the tracking coil 35. In this embodiment, the upright portion 32 cis widely formed in the width direction shown in FIG. 6, in order toincrease rigidity of the yoke member 32. However, the upright portion 32c may be divided into two portions such that the magnet 39 is attachedto one of them by bonding or the like and the magnet 40 is attached tothe other. Further, the magnet 40 is disposed in the yoke member 32 andis magnetized so that a magnetic pole thereof is exposed on the surfacefacing the tracking coil 35 in an order of the N pole and the S polefrom the inside in the width direction shown in FIG. 6.

The magnet 41 is attached on the upright portion 32 b and is provided soas to face the tracking coil 36. Further, the magnet 41 is disposed inthe yoke member 32 and is magnetized so that a magnetic pole thereof isexposed on the surface facing the tracking coil 36 in an order of the Npole and the S pole from the inside in the width direction shown in FIG.6.

The magnet 42 is attached on the upright portion 32 a and is provided soas to face the focus coil 34 and the sub-tracking coil 38. Further, themagnet 42 is disposed in the yoke member 32 and is magnetized so that amagnetic pole thereof is exposed on the surface facing the focus coil 34and the sub-tracking coil 38 in an order of the S pole and the N pole inthe height direction of FIG. 7 from the bottom surface toward the objectlenses 10 and 13.

Hereinafter, the details of the respective sections will be described.

First, the short wavelength optical unit 1 will be described withreference to FIGS. 9 and 10. FIG. 9 clearly shows a dispositionalrelationship between the respective sections, and FIG. 10 is a sectionalview of the short wavelength optical unit 1.

At least the light source section 1 a, the light receiving sections 1 band 1 c, and the optical member 1 d are directly or indirectly attachedto a loading section 43. Further, the back end of the loading section 43is attached to a holding member 44. The attachment portion 43 c of theloading section 43 with respect to the holding member 44 is formed in aconvexly curved shape, and similarly, the attachment portion of theholding member 44 with respect to the loading section 43 is formed in aconcavely curved shape. The loading section 43 is combined with theholding member 44. Further, as the curved-shaped portions thereof aremoved so as to slide, the loading section 43 and the holding member 44are positioned in a desired positional relationship. After that, theloading section 43 and the holding member 44 are fixed to each other bya metallic adhesive such as solder or an organic adhesive.

The loading section 43 is provided with a light source housing section43 a which can house at least a portion of the light source section 1 a.After being housed in the light source housing section 43 a, the lightsource section 1 a is bonded by a bonding material so as not to bedetached from the light source housing section 43 a. Further, athrough-hole 43 b is provided in a portion facing the light-emittingportion of the light source section 1 a so as to communicate with thelight source housing section 43 a. The light emitted from the lightsource section 1 a passes through the through-hole 43 b so as to beguided to the optical member 1 d. Although the details of the opticalmember 1 d will be described below, the optical member 1 d includes atleast an optical section 46 having an inclined surface 46 a and anoptical section 47 having a plurality of inclined surfaces formedtherein. The loading section 43 has a light receiving section attachingportion 48 integrally formed, the light receiving section attachingportion 48 facing the optical member 1 d. The light receiving sectionattaching portion 48 is provided with a through-hole 45. In the side ofthe light receiving section attaching portion 48 opposite to the opticalmember 1 d, the light receiving section 1 b is attached through aflexible printed board 49 by a technique such as bonding. Although theflexible printed board 49 is omitted and is shown in FIG. 9 or 10, theflexible printed board 49 electrically connects the light receivingsection 1 b to another member and is provided with a through-hole 49 a.The light from the optical member 1 d is guided to the light receivingsection 1 b through the through-holes 45 and 49 a. Further, as evidentfrom FIG. 10, a light receiving section attaching portion 50 isintegrally provided in the loading section 43 so as to face the lightreceiving section attaching portion 48, and the optical member 1 d isdisposed between the light receiving section attaching portions 48 and50. The light receiving section attaching portion 50 is provided with athrough hole (not shown), and the light receiving section 1 c isattached to the light receiving section attaching portion 50 by atechnique such as bonding. The light from the optical section 46 passesthrough the through-hole of the light receiving attaching portion 50(not shown) so as to be incident on the light receiving section 1 c.

Next, the optical sections 46 and 47 of the optical member 1 d will bedescribed in detail with reference to FIG. 11.

The short-wavelength light emitted from the light-emitting point of thelight source section 1 a is guided to the optical section 46 through acover glass 51 provided in a portion serving as a light-emission windowof the light source section 1 a. The light incident on a plane 46 bprovided substantially parallel to the cover glass 51 of the opticalsection 46 passes through the optical section 46, and the light incidenton the inclined surface 46 a inclined to the plane 46 b is reflected soas to be incident on the light receiving section 1 c (which is not shownin FIG. 11). The lights are used for monitoring an optical output. Onthe inclined surface 46 a, a reflecting section is formed of adielectric multilayer or metallic film. Most of light passing throughthe optical section 46 passes through a plane 46 c providedsubstantially parallel to the plane 46 b so as to be guided to theoptical section 47. The plane 46 c has a dimming filter (not shown)formed thereon, and light dimmed by the dimming filter is guided to theoptical section 47. Although the dimming filter has varioustransmittances, the transmittance thereof is adjusted by a spread angleof light emitted from the light source section 1 a. That is, when aspread angle of light from the light source section 1 a is large, thetransmittance of the dimming filter becomes small. Alternately, when aspread angle of light from the light source section 1 a is small, thetransmittance of the dimming filter becomes large. As the transmittanceof the dimming filter is adjusted by a spread angle of light from thelight source section 1 a, it is possible to prevent undesired occurrenceof data erasing which is caused by excessively intensive light outputwhen recording or reproducing is performed on a single-layer disk ormulti-layer disk. Specifically, a spread angle of light emitted from thelight source section 1 a is previously classified into predeterminedranges. Further, a dimming filter having a different transmittance isprovided in each of the classified light source sections 1 a, therebyobtaining an excellent recording/reproducing characteristic with respectto an optical disk. The dimming filter is formed of a dielectricmultilayer film or metallic film. When transmittance is adjusted and adielectric multilayer film is used, it is possible to adjust aconstituent material or film construction thereof or a thicknessthereof. When a metallic film is used, it is possible to adjust aconstituent material or thickness thereof.

The light passing through the plane 46 c is incident on the opticalsection 47. Between the optical sections 46 and 47, a gap is provided ata predetermined distance. The optical section 47 is formed in arectangular parallelepiped shape as a whole. On the bottom surface 53 onwhich the light from the light source section 1 a is incident, a lightabsorbing film having a function of absorbing light is provided exceptfor a predetermined region. The light absorbing film prevents the lightemitted from the light source section 1 a from being incident on theoptical section 47 from a place excluding a predetermined portion. Atleast some of light, which is emitted from the light source 1 a so as topass through the optical section 46, is incident on the inside of theoptical section 47 from a portion where the light absorbing film of thebottom surface 53 is not disposed.

The optical section 47 is constructed by bonding blocks 58 to 61 formedof transparent glass or the like. An inclined surface 54 is formed on abonding portion between the block 58 and the block 59, an inclinedsurface 55 is formed between the block 59 and the block 60, and aninclined surface 56 is formed between the block 60 and the block 61.Inside the optical section 47, at least the inclined surfaces 54, 55,and 56 are provided, and the end portions of the inclined surfaces 54,55, and 56 are exposed to the surface of the optical section 47. Theinclined surface 54 is provided with a first polarized beam splitter,and the inclined surface 55 is provided with a second polarized beamsplitter. Although both of the first and second polarized beam splittersare directly formed in the block 59, the first polarized beam splittermay be formed in the block 58 and the second polarized beam splitter maybe formed in the block 60. Both of the first and second polarized beamsplitters have a function of transmitting p-polarization light(hereinafter, abbreviated to a p-wave) and reflecting s-polarizationlight (hereinafter abbreviated to an s-wave). Further, at least thefirst and second polarized beam splitters may be provided in a portionwithin the optical section 47 through which light mainly passes. In thisembodiment, however, the first and second polarized beam splitters areprovided on the entire inclined surfaces 54 and 55, in consideration ofproductivity. On the inclined surface 56, a reflective film and ahologram (the same as the hologram 1 e shown in FIG. 1) are formed, thehologram 57 generating astigmatism.

The light passing through the bottom surface of the optical section 47from the light source section 1 a so as to be incident on the opticalsection 47 is an s-wave. The light is reflected by the first polarizedbeam splitter provided on the inclined surface 54 so as to be incidenton the second polarized beam splitter formed on the inclined surface 55.As described above, the second polarized beam splitter also reflects ans-wave. Therefore, the light incident on the second polarized beamsplitter is reflected so as to be emitted from the top surface 62 z ofthe optical section 47 and then passes through the above-describedmembers so as to be guided to the optical disk 2. Further, the lightreflected by the optical disk 2 is converted into a p-wave by the actionof the quarter wavelength member 9 a and is again incident on theoptical section 47 from the top surface 62 z of the optical section 47.At this time, the portion where the light is emitted from the opticalsection 47 toward the optical disk 2 and the portion where the lightreflected from the optical disk 2 is incident are located in thesubstantially same position. Since the light reflected by the opticaldisk 2 so as to return to the optical section 47 is a p-wave asdescribed above, the light is transmitted through the second polarizedbeam splitter provided on the inclined surface 55 so as to be incidenton the inclined surface 56. The inclined surface 56 is provided with thereflective hologram 57 generating astigmatism, and the reflected lightfrom the optical disk 2 is separated in predetermined directions by thehologram 57 such that a focus error signal can be obtained. Since thelight reflected by the inclined surface 56 is a p-wave, the light isonce again transmitted through the second polarized beam splitter and isthen transmitted through the block 59. Further, since the firstpolarized beam splitter also has a property of transmitting a p-wave asdescribed above, the light is transmitted though the first polarizedbeam splitter and is then transmitted through the block 58. Further, thelight is emitted outside the optical section 47 and is then incident onthe light receiving section 1 b.

Next, an example of the light source section 1 a will be described withreference to FIGS. 12 and 13.

As shown in FIGS. 12 and 13, the light source section 1 a is composed ofthe following members. First, the light source section 1 a has a base 62formed of a metallic material. In both of short-side portions of thebase 62, a concave portion 62 a is provided which is used in adjustingthe position of the light source section 1 a. Further, through-holes 62b and 62 c are provided. Although not shown in the drawing, anotherthrough-hole is provided in addition to the through-holes 62 b and 62 c.The cover member 63 is bonded to the base 62 by welding or soldering,and a rectangular through-hole 64 is provided on the top surface of thecover member 63 on which a cover glass 65 (the same as the cover glass51 of FIG. 11) is attached by bonding so as to block the through-hole64. The cross-section of the cover member 63 is formed in an ellipticalor oval shape. In a region surrounded by the base 62 and the covermember 63, a block 66 is provided which is formed of copper or a copperalloy having excellent heat conductivity. The block 66 is bonded to thebase 62 by welding or a metallic bonding material. The cross-section ofthe block 66 is formed in a substantially semi-circular shape. On theflat portion of the block 66, a semiconductor laser element 68 isprovided through a sub-mount 67 formed of a metallic material.Accordingly, the sub-mount 67 and the semiconductor laser element 68 aswell as the block 66 are disposed within a region surrounded by the base62 and the cover member 63. Further, the light-emitting surface of thesemiconductor laser element 68 is disposed so as to face the cover glass65, and light is emitted outside from the cover glass 65. In thethrough-holes 62 b and 62 c and the other through-hole provided in thebase 62, rod-shaped terminals 69, 70, and 71 are respectively inserted.Portions of the terminals 69, 70, and 71, which are inserted into thethrough-holes 62 b and 62 c and the other through-hole, are attached tothe base 62 though insulating materials such that the insulating betweenthe base 62 and the terminals 69, 70, and 71 is secured. The leading endportions of the terminal 69, 70, and 71 are formed so as to projectwithin the region surrounded by the base 62 and the cover member 63. Theterminal 69 and the sub-mount 67 are connected through gold wire 69 a,and the terminal 69 and the n-type GaN side of the semiconductor laserelement 68 are electrically connected through the sub-mount 67. Further,the terminal 70 and the p-type GaN side of the semiconductor laserelement 68 are electrically connected through gold wire 70 a.Accordingly, electric power is supplied to the semiconductor laserelement 68 through the terminals 69, 70, and 71, thereby emittingshort-wavelength light.

As for the above-described semiconductor laser element 68, it ispreferable to use a GaN-based semiconductor laser element in which anactive layer (gallium nitride with the emission center, such as In orthe like) is provided between a p-type GaN layer and n-type GaN layer.The semiconductor layer element 68 emits light with a wavelength of 400to 415 nm. It is natural to use a semiconductor laser element based onother materials, which emits different short-wavelength laser.

In the semiconductor laser element 68 having a rectangularparallelepiped shape, the p-type GaN layer, the n-type GaN layer, andthe active layer are laminated substantially parallel to a long-sidedirection X. As for the semiconductor laser element 68, a structure isused, in which the n-type GaN layer, the active layer, and the p-typeGaN layer are sequentially laminated from the side of the sub-mount 67.However, another structure may be used, in which the p-type GaN layer,the active layer, and the n-type GaN layer are sequentially laminatedfrom the side of the sub-mount 67. In any case, the laminated directionof the active layer of the semiconductor laser element 68 is notparallel to the long side 62 d of the base 62 (in this embodiment, thelaminated direction perpendicularly crosses the long side 62 d).Further, since the long side 62 d of the base 62 is attached to the base15 so as to be perpendicular to the thickness direction of the base 15,the active layer of the semiconductor laser element 68 is laminatedsubstantially parallel to the thickness direction of the base 15. Here,in order to make the optical disk drive slim, the long side 62 d of thebase 62 is attached so as to be substantially perpendicular to thethickness direction of the base 15. However, in terms of effectivelyusing short-wave laser, the laminated direction of the semiconductorlaser element 68 may be substantially parallel to the thicknessdirection of the base 15.

In other words, the long-side portion having a rectangular cross-sectionis bonded to the sub-mount 67 in the relationship between the base 62and the semiconductor laser element 68. Therefore, the long side 62 d ofthe base 62 is not parallel to the long-side direction X of thesemiconductor laser element 68 (in this embodiment, the long-sidedirection X perpendicularly crosses the long side 62 d). In such aconstruction, the cross-section of light discharged from thesemiconductor laser element 68 can be discharged so that the long axisof the elliptical intensity distribution of emitted light issubstantially parallel to the long side 62 d of the base 62. As shown inFIG. 14, reference numeral 72 represents an axis substantially parallelto the long side 62 d of the base 62, reference numeral 74 is an outlineof light in which the intensity distribution of light discharged fromthe semiconductor laser element 68 is indicated by a line whereintensity becomes uniform, and reference numeral 73 represents a longaxis of the elliptical outline 74 of discharged light. In thisembodiment, an angle θ at which the axis 72 and the long axis 73 crosseach other is not 90 degrees, as shown in FIG. 14A. However, the axis 72and the long axis 73 cross each other at different angles, as shown inFIGS. 14B and 14C. The angle θ is defined as the minimum angle amongangles at which the axis 72 and the long axis 73 cross each other. Thatis, the angle θ is more than 0 degree and less than 90 degrees. In otherwords, the axis 72 and the long axis 73 are parallel to each other, asshown in FIG. 14B, and the long axis 73 and the axis 72 cross each otherat predetermined angles θ, as shown in FIGS. 14B to 14F. At this time,it is preferable that the angle θ at which the axis 72 and the long axis72 cross each other is set to be in the range of 0 to 45 degrees. Morepreferably, the angle θ is set to be in the range of 0 to 30 degrees.Further, the angle θ is set to be in the range of 0 to 10 degrees.Naturally, it is most preferable that the long axis 73 and the axis 72become substantially parallel to each other (the angle θ is almost 0degree), as shown in FIG. 14B. In the above example, the axis 72 is setto be parallel to the long side 62 d of the base 62. However, the axis72 can be also defined in the relationship with other constituentmembers, as follows. That is, the axis 72 can be defined as an axiswhich is parallel to the main surface of the mount optical disk 2 and isperpendicular to the direction of light emitted from the cover glass 65of the light source section 1 a. Alternately, the axis 72 can be definedas an axis which is perpendicular to the thickness direction of the base15 shown in FIG. 2 and is also perpendicular to the direction of lightemitted from the cover glass 65 of the light source section 1 a.Further, the axis 72 can be defined as an axis which is parallel to thebottom surface of the base 15 and is perpendicular to the direction oflight emitted from the cover glass 65 of the light source section 1 a.Furthermore, the axis 72 can be defined as an axis which isperpendicular to the rotating shaft of the spindle motor 25 and is alsoperpendicular to the direction of light emitted from the cover glass 65of the light source section 1 a.

As the long axis in the outline of light emitted from the light sourcesection 1 a is set in such a positional relationship, it is possible toincrease utilization efficiency of light. If the light source section 1a having the same output is used, it is possible to irradiate lighthaving a larger output onto the optical disk 2. If the intensity oflight irradiated on the optical disk 2 is set to the same magnitude, itis possible to use a light source section 1 a with a smaller output.

Hereinafter, the principle will be described in detail with reference toFIG. 15.

FIG. 15A shows a case where the axis 72 and the long axis 73perpendicularly cross each other, that is, a case where the outline isformed in a longitudinally-long elliptical shape. In this case, when thelight intensity of the center Q (point where the long axis and the shortaxis cross each other) of the outline 74 is set to 1, light of a regionup to a portion having a predetermined proportion of light intensity inthe direction along the axis 72 is used. For example, the predeterminedproportion is 0.6 (although the proportion is determined depending on aspecification, it is typically in the range of 0.3 to 0.8), and thelight of a circular region 75, in which left and right distances fromthe center Q are set to L1 and L2, can be used. That it, the light ofthe elliptical region 75 having a diameter of L1+L2 can be used. In thisembodiment, since L1 is substantially equal to L2 (L1≈L2), a region oflight to be substantially used becomes the circular region 75 with aradius of L1 or L2. In the case of FIG. 15A, the outline is formed in alongitudinally-long elliptical shape. Therefore, the distances L1 and L2from the center Q to where a light intensity becomes 0.6 of the lightintensity at the center Q become relatively small in the direction ofthe axis 72, and a region with available light intensity is small. Inthe optimal embodiment shown in FIG. 15B, light of a region up to aportion having a predetermined proportion of light intensity is used.For example, the predetermined proportion is 0.6 (although theproportion is determined depending on a specification, it is typicallyin the range of 0.3 to 0.8), and the light of a circular region 75, inwhich left and right distances from the center Q are set to L3 and L4,can be used. That it, the light of the circular region 75 having adiameter of L3+L4 can be used. In this embodiment, since L3 issubstantially equal to L4 (L3=L4), a region of light to be substantiallyused becomes the circular region 75 with a radius of L3 or L4. In thecase of FIG. 15B, the outline 74 is formed in a laterally-longelliptical shape. Therefore, the distances L3 and L4 from the center Qto where a light intensity becomes 0.6 of the light intensity at thecenter Q become relatively large in the direction of the axis 72, and aregion with available light intensity becomes much larger than in theexample of FIG. 15A, which makes it possible to effectively use light.That is, the following relationship is established: L1<L3 and L2<L4.

In this embodiment, the long axis 73 of elliptically-shaped lightemitted from the light source section 1 a is set at a predeterminedangle (including 0 degree) with respect to the axis 72, as describedabove. Therefore, as the long side 62 of the base 62 is attached towardthe base 15 as shown in FIGS. 12 and 13, the long axis of theelliptically-shaped light emitted from the light source section 1 a canbe set to be substantially parallel to the base 15, and the height ofthe light source section 1 a does not become large. Accordingly, it ispossible to make the device slim. In this embodiment, it is assumed thatthe optical disk drive has a thickness of, preferably, less than 18 mm,or more preferably, less than 15 mm, or most preferably, less than 13mm. Therefore, attaching the light source section 1 a at a low level canimplement such an optical disk drive. Further, when the axis 72 and thelong axis 73 are set at a predetermined angle (larger than 0 degree andless than 90 degrees), the following method is used in order to make thedevice slim. The light source section 1 a itself is rotated at apredetermined angle so as to be attached (in this case, when the lightsource section 1 a is attached, the attachment height becomes slightlylarge), the block 66 in the light source section 1 a is rotated by apredetermined amount so as to be attached to the base 62, or thesemiconductor laser element 68 is attached to the block 66 so as to beinclined to the long side 62 d.

Next, the long wavelength optical unit 3 will be described withreference to FIG. 16.

A loading section 76 is provided with a light source holding section 76a. The light source 3 a is bonded to the light source holding section 76a by a bonding material such as solder, lead-free solder, orlight-curing resin. On the light source holding section 76 a of theloading section 76, the optical member 3 d is attached. Further, thelight receiving sections 3 b and 3 c are attached to the loading section76 by a bonding material such as light-curing resin so as to interposethe optical member 3 d. The light source section 3 a covers at least aportion of a lead frame 77 through a molding member 78 such as resin,and a semiconductor laser element 79 is attached on the lead frame 77 towhich terminals 77 a to 77 c are electrically connected. As describedabove, the semiconductor laser element 79 emitting light with awavelength of 640 to 800 nm is constructed so as to emit light with onekind of wavelength or a plurality of lights with plural kinds ofwavelengths. In this embodiment, the semiconductor laser element 79 isconstructed so as to emit a light flux with a wavelength of about 660 nm(red: corresponding to DVD) and a light flux with a wavelength of about780 nm (infrared: corresponding to CD). The semiconductor laser element79 as a mono-block element is constructed so as to emit two lightfluxes. However, an element emitting one light flux as one block may beprovided on the plurality of lead frames 77.

The optical member 3 d is composed of two optical sections 80 and 81.The optical section 80 is formed in a plate shape. Although not shown, afilm for coping with stray light is formed so that unnecessary lightemitted from the light source section 3 a does not reach the opticalsection 81. That is, the film for coping with stray light has an openingsuch that most of light is guided to the optical section 81 through theopening. Further, the film is formed of such a material that absorbslight incident on a portion excluding the opening. Further, a hologramhaving a wavelength selection property is provided, which acts on lightcorresponding to CD but hardly act on light corresponding to DVD. Thehologram separates light corresponding to CD into three beams. Theoptical section 81 is provided on the optical section 80 and is formedby bonding blocks 82 to 85 made of transparent glass. An inclinedsurface 86 is formed in a bonding portion between the block 82 and theblock 83, an inclined surface 87 is between the block 83 and the block84, and an inclined surface 88 is formed between the block 84 and theblock 85. Inside the optical section 81, at least the inclined surfaces86, 87, and 88 are provided, and the end portions of the inclinedsurfaces 86, 87, and 88 are exposed to the surface of the opticalsection 81.

The inclined surface 86 has at least one of a reflective film andhologram provided in a transmitted portion of light such that 3 to 15%of light emitted from the light source section 3 a is reflected.Further, the inclined surface 86 has a dielectric multilayer formedthereon. The dielectric multilayer transmits a p-wave of lightcorresponding to CD and light corresponding to DVD and reflects ans-wave. The light reflected by the inclined surface 86 is incident onthe light receiving section 3 c so as to be used for controlling anoptical output of the light source section 3 a. Further, the inclinedsurface 87 has a dielectric multilayer formed thereon. The dielectricmultilayer transmits a p-wave of light corresponding to CD and lightcorresponding to DVD, reflects an s-wave of light corresponding to CD,and transmits an s-wave of light corresponding to DVD. Further, theinclined surface 88 has a dielectric multilayer or metallic filmreflecting light. In this embodiment, the inclined surface 88 isprovided with a reflective hologram 3 e.

When the light corresponding to CD emitted from the light source section3 a is incident on the optical section 80, stray light thereof isremoved, and the light is separated into three beams on the optical disk2 by the hologram having a wavelength selection property. Further, whenthe light is incident on the optical section 81 from the optical section80, some of the light is reflected by the inclined surface 86 so as tobe incident on the light receiving section 3 c, and the other of thelight which is a p-wave passes through the inclined surface 86 so as tobe incident on the block 83 and is then guided to the inclined surface87. In the inclined surface 87, the light corresponding to CD which is ap-wave passes through the block 84 so as to be emitted from the surfaceof the block 84. Further, the light reflected by the optical disk 2becomes an s-wave by the action of the quarter wavelength member of theoptical part 11 and is again incident on the top surface of the block 84so as to be incident on the inclined surface 87. Since the inclinedsurface 87 is provided with a film having a function of reflecting ans-wave of light corresponding to CD, the light corresponding to CDreflected from the optical disk 2 is reflected by the inclined surface87 so as to be reflected by the inclined surface 88. Further, the lightpasses through the block 84 so as to be again incident on the inclinedsurface 87. Since the inclined surface 87 is provided with a filmreflecting an s-wave of light corresponding to CD as described above,the light is again reflected by the inclined surface 87 and then passesthrough the block 84 so as to be guided into the light receiving section3 b. The light incident on the light receiving section 3 b is convertedinto an electrical signal such that an RF signal, a tracking errorsignal, or a focus error signal is generated. The reflective hologram 3e provided on the inclined surface 88 separates the reflected light fromthe optical disk 2 into a plurality of lights. The respective lights areguided into a predetermined place of the light receiving section 3 b,thereby generating a focus error signal.

When the light corresponding to DVD emitted from the light sourcesection 3 a is incident on the optical section 80, stray light thereofis removed, and the light is incident on the optical section 81. Thehologram having a wavelength selection property, provided in the opticalsection 80, does not act on the light corresponding to DVD. Further,when the light is incident on the optical section 81 from the opticalsection 80, some of the light is reflected by the inclined surface 86 soas to be incident on the light receiving section 3 c, and the other ofthe light passes through the inclined surface 86 so as to be incident onthe block 83 and is guided into the inclined surface 87. Since the lightcorresponding to DVD is a p-wave in the inclined surface 87, the lightpasses through the block 84 so as to be emitted from the top surface ofthe block 84. Further, the light reflected by the optical disk 2 becomesan s-wave and is again incident on the top surface of block 84 so as tobe incident on the inclined surface 87. Since the inclined surface 87 isprovided with a film having a function of transmitting lightcorresponding to DVD, the light corresponding to DVD reflected from theoptical disk 2 passes through the inclined surface 87. Further, thelight passes through the block 83 so as to be incident on the inclinedsurface 86. Since the inclined surface 86 reflects s-wave lightcorresponding to DVD, the light corresponding to DVD is reflected by theinclined surface 86 and passes through the block 83 so as to be againincident on the inclined surface 87. As described above, however, theinclined surface 87 is provided with a film having a function oftransmitting light corresponding to DVD. Therefore, the light passesthrough the inclined surface 87 so as to be guided into the lightreceiving section 3 b. The light incident on the light receiving section3 b is converted into an electrical signal such that an RF signal, atracking error signal, or a focus error signal is generated.

FIG. 16 illustrates an inward/outward path of light corresponding to CD.

Next, the beam shaping lens 4 used in this embodiment will be described.

As shown in FIG. 17, the beam shaping lens 4 includes a lighttransmitting section 4 d having a convex portion 4 a and a concaveportion 4 b and attachment portions 4 c provided to interpose the lighttransmitting section 4 d. Although the light transmitting section 4 dand the attachment portions 4 c are integrally molded in thisembodiment, the light transmitting section 4 b and the attachmentportions 4 c may be constructed separately so as to be bonded to eachother by an adhesive or the like.

As shown in FIG. 17A, short-wavelength light emitted from the shortwavelength optical unit 1 has an elliptical cross-sectional shapeimmediately before being incident on the beam shaping lens 4. However,after passing through the beam shaping lens 4, the light becomes lighthaving a circular cross-sectional shape due to the curvature radius orpredetermined curved shape of the convex or concave portion 4 a or 4 b.Similarly, when the light reflected by the optical disk 2 or the likepasses through the beam shaping lens 4, the light having a circularcross-sectional shape is converted into light having an ellipticalcross-sectional shape.

Next, the optical part 5 used in this embodiment will be described withreference to FIG. 18.

The optical part 5 includes substantially square-shaped and plate-shapedsubstrates 5 a and 5 b formed of transparent glass and polarizingsections 5 c and 5 d. The polarizing section 5 c and 5 d are interposedbetween the substrates 5 a and 5 b. The polarizing section 5 c activelyacts on s-wave light emitted from the short wavelength optical unit 1,but hardly acts on p-wave light reflected by the optical disk 2.Further, the polarizing section 5 d hardly acts on s-wave light emittedfrom the short wavelength optical unit 1, but actively acts on p-wavelight reflected by the optical disk 2. In the optical part 5, the lightemitted from the short wavelength optical unit 1 sequentially passesthrough the substrate 5 a, the polarizing section 5 c, the polarizingsection 5 d, and the substrate 5 b, and the light reflected by theoptical disk 2 sequentially passes through the substrate 5 b, thepolarizing section 5 b, the polarizing section 5 d, the polarizingsection 5 c, and the substrate 5 a. As shown in FIG. 18B, the polarizingsection 5 c has a hologram 5 e formed in a substantially rectangularshape. The hologram 5 e having a wavelength selection property is formedof an optically anisotropic resin material. As shown in FIG. 18B, thehologram 5 e is formed in a rectangular shape such that the end of thediameter of an incident light flux protrudes from the long side thereof.Although not shown, the polarizing section 5 c is constructed by fillingisotropic resin in the hologram 5 e. As one manufacturing method, thehologram 5 e is manufactured on the substrate 5 a by a well-knownmethod, and isotropic resin is filled in the clearance of the hologram 5e. As shown in FIG. 18C, an amount of incident light is indicated by adotted line in the X axis of FIG. 18B. When light passes through thepolarizing section 5 c, an amount of light decreases as a whole, asindicated by a solid line. Further, as shown in FIG. 18 d, an amount ofincident light is indicated by a dotted light in the Y axis of FIG. 18B.When light passes through the polarizing section 5 c, an amount of lightdecreases in a portion where an amount of incident light is large. Assuch, the polarizing section 5 c decreases an amount of light in aportion where an amount of light is large. Therefore, RIM intensity(ratio of the intensity of the outermost light flux to the centerintensity) can be increased, short-wavelength light can be condensedinto a small spot on the optical disk 2, and at least one of recordingand reproducing can be performed onto the high-density optical disk 2.That is, the polarizing section 5 c serves as a RIM intensity correctingfilter which does not act in the X-axis direction where the RIMintensity is strong, but acts only in the Y-axis direction where the RIMintensity is weak.

In the polarizing section 5 d, a hologram (not shown) having polarizedlight selection characteristics is provided on the substrate 5 b, thehologram being formed of optically anisotropic resin. In the hologram,isotropic resin is filled. The hologram composing a portion of thepolarizing section 5 d has a function of separating light reflected fromthe optical disk 2 into predetermined light fluxes such that a trackingerror signal is mainly generated.

As one manufacturing method, the following method is exemplified. Thepolarizing sections 5 c and 5 d are formed on the substrates 5 a and 5b, respectively. Then, the polarizing sections 5 c and 5 b are disposedto face each other and are then bonded to each other by an adhesive suchas resin, thereby forming the optical part 5.

Next, the relay lens 6 will be described in detail.

In detail, the relay lens 6 is formed in such a shape as shown in FIG.19. That is, the relay lens 6 includes a light transmitting section 6 a,a plurality of projecting sections 6 b, and an outer ring section 6 c.The light transmitting section 6 a is provided so that light passesthrough at least a portion thereof. The plurality of projecting sections6 b are provided around the light transmitting section 6 a and,preferably, in a radial pattern. In the outer ring section 6 c, theoutside thereof is formed in a substantially circular shape, in whichthe projecting sections are provided. In this embodiment, the lighttransmitting section 6 a, the projecting sections 6 b, and the outerring section 6 c are integrally formed. The respective sections may beconstructed separately so as to be bonded to each other.

The base 15 has an attachment section 15 a provided so as to be raised.The attachment section 15 a has a concave section 15 b provided with astep portion 15 c. The relay lens 6 is inserted from an insertiondirection shown in FIG. 19. The concave section 15 b provided with thestep portion 15 c prevents the relay lens 6 from being detached towardthe long wavelength optical unit 3. Further, although not shown, athrough-hole is provided in a portion facing the light transmittingsection 6 a of the inserted relay lens 6. Accordingly, as shown in FIG.19, the light emitted from the long wavelength optical unit 3sequentially passes through the through-holes provided in the lighttransmitting section 6 a and the attachment section 15 a so as to bedirected to the beam splitter 7.

With a thin pin (not shown) being abutted on the projecting section 6 b,the relay lens 6 is displaced at a predetermined angle by an operator oran automatic adjusting device, thereby correcting astigmatism. Further,the outer ring section 6 c is substantially abutted on the inner wall ofthe concave section 15 b, and the outer shape of the outer ring section6 c is formed in a circular shape, even though some projections orconcave portions are present thereon. Therefore, the relay lens 6 isrotatably held by such a thin pin as described above. After the relaylens 6 is rotated at a predetermined angle so as to correct astigmatism,an instant adhesive or light-curing adhesive is provided and hardenedover at least the relay lens 6 and the attachment section 15 a, therebyfixing the relay lens 6 to the attachment section 15 a. At this time, itis preferable that an adhesive is provided in the concave section 15 bof the attachment section 15 a. It is more preferable to consider anapplying method and an applied amount of adhesive such that the adhesiveis not applied into the light transmitting section 6 a.

Next, the beam splitter 7 will be described in detail.

As shown in FIG. 20, the outer shape of the beam splitter 7 is formed ina substantially rectangular parallelepiped shape or a substantiallycubical shape. As described above, the beam splitter 7 is constructed bybonding the transparent members 7 b and 7 c and has the inclined surface7 a formed by bonding between the transparent members 7 b and 7 c. Asshown in FIG. 20, the inclined surface 7 a is formed at an angle ofabout 45 degrees with respect to a bottom side 7 f of the side surface.However, depending on a specification or the outer shape of the beamsplitter 7, the angle is suitably determined to be a predeterminedangle. The transparent members 7 b and 7 c made of a glass material suchas BK7 or the like are formed in a triangle pole shape. As shown in FIG.20, the inclined surface 7 a has a laminate section 7 d and a bondingsection 7 e.

The laminate section 7 d is constructed by alternately laminating a lowrefraction film and a high refraction film. In this embodiment, a SiO₂film is used as a low refraction film, and a Ta₂O₅ film is used as ahigh refraction film. Further, the thicknesses of the high refractionfilm and the low refraction film, respectively, are set to be in therange of 10 to 400 nm. In this embodiment, the surface where thelaminate section 7 d of the transparent member 7 c is provided ispreferably subjected to a grinding process or surface treatment. Then,SiO₂ films and Ta₂O₅ films are laminated in an order of SiO₂, Ta₂O₅,SiO₂, Ta₂O₅, . . . , SiO₂, Ta₂O₅, and SiO₂ by using a thin film formingtechnique such as sputtering or deposition, thereby forming the laminatesection 7 d. In this embodiment, more than 20 thin film sets of SiO₂film and Ta₂O₅ film are laminated (considering a yield ratio or amanufacturing cost, it is preferable to laminate less than 35 sets). Ifthe SiO₂ films and Ta₂O₅ films are counted one by one, the laminatesection 7 d is composed of 40 to 70 layers. Further, it is advantageousto set the actual thickness of the laminate section 7 d to 2 to 10 nm interms of characteristic and productivity.

When the laminate section 7 d is constructed in such a manner, theformation thicknesses of the respective layers (in the abovedescription, the SiO₂ films and the Ta₂O₅ films) are adjusted, so thatlight with a predetermined wavelength is transmitted and light withother wavelengths is reflected. In this embodiment, the laminate section7 d is constructed so as to transmit red light (with a wavelength ofabout 660 nm) and infrared light (with a wavelength of about 780 nm) andto reflect short-wavelength light (with a wavelength of about 405 nm).

Between the laminate section 7 d and the transparent member 7 b, abonding section 7 e is provided, and a Si-based adhesive is preferablyused in the bonding section 7 e. The Si-based adhesive is hardlydegraded by short-wavelength light. The Si-based adhesive is preferablyused in an optical pickup device using light with a wavelength of about405 nm, as in this embodiment. Further, the bonding section 7 e may beformed of glass or other resin materials. As the thickness of thebonding section 7 e is set to 3 to 15 nm (preferably, 8 to 12 nm), thebonding between the transparent members 7 b and 7 c can be reliablyperformed, and productivity can be increased. Further, the feature ofthis embodiment is that short-wavelength light is incident from thebottom side 7 f. Therefore, with the laminate section 7 d being providedon the transparent member 7 c without the bonding member 7 e, thebonding section 7 e can be suppressed from being degraded byshort-wavelength light.

Next, the collimator lens 8 and the driving mechanism thereof will bedescribed.

As shown in FIG. 21, the lead screw 8 c, the gear group 8 d, and thedriving member 8 e are fixed to the base 89. In this embodiment, astepping motor is used as the driving member 8 e, and a motor gear 90 isfixed to the rotating shaft of the driving member 8 e. Further, a trainshaft 91 is rotatably attached to the base 89, a train gear 92 is fixedto the train shaft 91, and a motor gear 90 is geared to the train gear92. Further, a pair of attachment sections 89 a and 89 b are integrallyprovided in the base 89. One end of the screw shaft 8 c is rotatablyheld by the attachment section 89 a, and the other end of the screwshaft 8 c is rotatably inserted into the attachment section 89 b. Ashaft gear 93 is fixed to the end of the screw shaft 8 c at theattachment 89 b, and the train gear 92 is geared to the shaft gear 93.That is, as the driving member 8 e rotates, the rotation driving forcethereof is transmitted to the screw shaft 8 c through the gear group 8 d(the motor gear 90, the train gear 92, and the shaft gear 93).

As such, the driving mechanism 94 having the respective members mountedthereon is attached to the base 15.

As shown in FIGS. 22 and 23, the slider 8 b having the collimator lens 8mounted thereon is movably attached to the pair of support members 8 aattached to the base 15. Further, the driving mechanism 94 is providedin the side of the support member 8 a such that the screw shaft 8 c ofthe driving mechanism 94 and the support member 8 a are substantiallyparallel to each other. A rack member 95 formed of an elastic materialsuch as a plane spring is attached to the slider 8 b by adhesive bondingor mechanical bonding, and the end of the rack member 95 is geared to aspiral groove provided in the screw shaft 8 c. Accordingly, if thecenter of the movable range of the slider 8 b is set to a referencepoint O for the sake of description, the slider 8 b isparallel-displaced from the reference point O toward the beam splitter 7or the inclined-right mirrors 9 and 12 by the rotation of the screwshaft 8 c. When the rotation direction or rotation speed of the screwshaft 8 c is changed, it is possible to adjust the moving direction orspeed of the slider 8 b. In this embodiment, since a stepping motor isused as the driving member 8 e, the position of the slider 8 b, that is,the position of the collimator lens 8 can be determined by the number ofpulses supplied to the driving member 8 e.

Although not shown, at least one of recording and reproducing can beperformed on the optical disk 2 (having a first recording layer and asecond recording layer) by using light from the short wavelength opticalunit 1, or recording and reproducing of information can be performed onthe optical disk 2 by using light corresponding to CD or DVD emittedfrom the long wavelength optical unit 2. In this case, the position ofthe collimator lens 8 is varied in order to reliably perform at leastone of recording and reproducing.

Accordingly, when at least one of recording and reproducing is performedon the first recording layer (which is positioned at a depth of 0.1 mmfrom the surface at the object lens 13) of the optical disk 2 by usinglight from the short wavelength optical unit 1, the collimator lens 8 ispositioned in a first position. When at least one of recording andreproducing is performed on the second layer (which is positioned at adepth of 0.075 mm from the surface at the object lens 13) of the opticaldisk 2 by using light from the short wavelength optical unit 1, thecollimator lens 8 is positioned in a second position. When at least oneof recording and reproducing is performed on the optical disk 2 by usinglight corresponding to CD emitted from the long wavelength optical unit3, the collimator lens 8 is positioned in a third position. When atleast one of recording and reproducing is performed on the optical disk2 by using light corresponding to DVD emitted from the long wavelengthoptical unit 3, the collimator lens 8 is positioned in a fourthposition. The first to fourth positions are positions of the collimatorlens 8 in the movable range of the slider 8 b. The first position andthe second position always differ from each other, and the thirdposition and the fourth position differ from at least one of the firstposition and the second position. That is, the first to fourth positionsare set to at least two different positions. The first position and thesecond position always differ from each other. Therefore, if the thirdposition and the fourth position can be positioned between the first andsecond positions, the movable range of the slider 8 b can be interposedtherebetween. However, the first to fourth positions are not limitedthereto. Next, one example of the positional relationship between thefirst to fourth positions will be described.

As shown in FIG. 22, the first position is set to a position of 0.83 mmfrom the reference point O toward the beam splitter 7, the secondposition is set to a position of 0.83 mm from the reference point Otoward the inclined-right mirrors 9 and 12, and the third and fourthpositions are set to a position of 1.9 mm from the reference point Otoward the inclined-right mirrors 9 and 12. Then, the position of thecollimator lens 8 is varied, and at least one of recording andreproducing can be reliably performed on the respective recording layersof the optical disk 2 regardless of the type of the optical disk 2.Depending on the optical disk 2 on which recording and reproducing isperformed using light from the short wavelength optical unit 1, thefirst and second positions are fine-adjusted toward the beam splitter 7or the inclined-right mirrors 9 and 12 while a distance of 1.66 mm ismaintained. Accordingly, it is possible to perform more precisecorrection of spherical aberration with respect to short-wavelengthlight. Similarly, the fourth position is fine-adjusted depending on theoptical disk 2 (in this case, DVD) mounted on the spindle motor 25.

An example of an operation according to the above-described constructionwill be described.

It is assumed that the slider 8 b is positioned in the home position bya separate sensor (not shown). Using a signal from the outside, acontrol member (not shown) judges whether recording/reproducing isperformed using light with a certain wavelength or whetherrecording/reproducing is performed on the first recording layer or thesecond recording layer. In accordance with the signal, the controlmember reads from a memory how many pulses are delivered to the drivingmember 8 e. At this time, the first to fourth positions are determinedby the wavelength of light at which recording/reproducing is performedor whether recording/reproducing is performed on the first recordinglayer or the second recording layer. It is determined at the time ofdesign in which direction and how much the slider 8 b existing in thehome position should be moved in order to position the collimator lens 8in the respective positions. Therefore, as the number of pulses requiredfor each operation is previously recorded in the memory, the collimatorlens 8 can be easily positioned in the optimal position (the first tofourth positions). The first to fourth positions can coincide with thehome position of the slider 8 b, and the reference point O can coincidewith the home position. Further, when a predetermined operation isterminated, the control member delivers pulses to the driving member 8 eso as to return the slider 8 b to the home position.

Next, the achromatic diffraction lens 14 will be described.

As shown in FIG. 24, the achromatic diffraction lens 14 includes a lighttransmitting section 14 d and an outer ring section 14 c surrounding theoutside of the light transmitting section 14 d. The surface 14 a of thelight transmitting section 14 d at the object lens 13 is formed in aconcave shape. On the surface 14 b facing the inclined-right mirror 12,a hologram is provided at a predetermined pitch and in a predeterminedshape. The light transmitting section 14 transmits short-wavelengthlight. As the pitch of the hologram provided on the surface 14 b isadjusted, it is possible to perform desirable correction of chromaticaberration. The achromatic diffraction lens 14 is formed in asubstantially circular shape, and the outer ring section 14 c isattached to the lens holder 16. In this embodiment, the lighttransmitting section 14 d and the outer ring section 14 d are integrallyformed. However, the light transmitting section 14 c and the outer ringsection 14 c may be constructed separately from each other. For example,the light transmitting section 14 d may be constructed so as to beembedded in the central portion of the outer ring section 14 c.

Next, the lens holder 16 and the suspension holder 17 will be describedwith reference to FIGS. 25 to 28. Further, members having the samereference numerals as those of FIGS. 6 and 7 have the same functions. Asdescribed above, the members of FIGS. 25 to 28 having the same referencenumerals as those of FIGS. 6 and 7 have the same functions. However, themembers shown in FIGS. 25 to 28 have a slightly different shape fromthose shown in FIGS. 6 and 7.

When at least one of recording and reproducing is performed on theoptical disk 2 at high double speed, the resonance frequency of the lensholder 16 needs to be increased. That is, when recording/reproducing isperformed at high double speed, the lens holder 16 is controlled so asto follow the surface wobbling of the lens holder 16. In this case, theresonance frequency of the lens holder 16 is increased so that the lensholder 16 is controlled in a region of less than the resonancefrequency. As one method of increasing the resonance frequency of thelens holder 16, it is exemplified to impart a high rigidity to the lensholder 16. In this embodiment, in order to impart a high rigidity to thelens holder 16, the entire portion or at least a portion of the lensholder 16 is formed of a material (hereinafter, referred to as acomposite material) in which fiber is dispersed into resin. As forresin, liquid crystal polymer, epoxy resin, polyimide-based resin,polyamide-based resin, acrylic resin or the like is preferably used. Asfor fiber, carbon fiber, carbon black, metallic fiber such as copper,nickel, aluminum, or stainless steel, or composite fiber is preferablyused. In this embodiment, the lens holder 16 is formed of a materialobtained by dispersing carbon fiber into liquid crystal polymer.

As shown in FIGS. 25 and 26, when the lens holder 16 and the suspensionholder 17 are formed of the composite material, the lens holder 16 andthe suspension holder 17 can have conductivity. Therefore, an insulatingfilm is formed on the suspensions 18 a to 18 f. In this case, betweenthe lens holder 16 and various coils, an insulating member is providedfor insulation. Alternately, various coils are composed of winding wiresubjected to insulating treatment. As such, the suspensions 18 a to 18 fprovided with an insulating film secures insulation properties withrespect to the lens holder 16 and the suspension holder 17 havingconductivity. Further, the insulated ends 98 and 99 of the suspensions18 a to 18 f are attached to bobbin receiving sections 96 and 97, whichare integrally provided in the lens holder 16, by insert molding. Theinsulated ends 100 and 101 of the suspensions 18 a to 18 f at thesuspension holder 17 are attached to the suspension holder 17 by insertmolding. Further, since the leading ends 102 and 103 of the suspensions18 a to 18 f at the lens holder 16 are not provided with an insulatingfilm, the leading ends 102 and 103 are electrically connected to variouscoils provided in the lens holder 16. Further, since the leading ends104 and 105 of the suspensions 18 a to 18 f at the suspension holder 17are not provided with an insulating film, the leading ends 104 and 105are connected to a flexible printed board (not shown).

As a modification of the embodiment shown in FIGS. 25 and 26, all thesuspensions 18 a to 18 f are not provided with an insulating film, butthe ends 106 and 107 of the suspensions 18 a to 18 f are provided withan insulating film as shown in FIGS. 27 and 28. Then, portions or theentire portions of the ends 106 and 107 are bonded to the bobbinreceiving sections 96 and 97, respectively. In the case of the entireportions, it is considered that the lens holder 16 does not come incontact with the suspensions 18 a to 18 f. In the modification of FIGS.27 and 28, portions of the ends 106 and 107 are bonded to the bobbinreceiving sections 96 and 97 in order to secure insulation properties.Further, an insulating film is also provided in the ends 108 and 109 ofthe suspensions 18 a to 18 f at the suspension holder 17, and at leastthe ends 108 and 109 and the suspension holder 17 are bonded. In themodification of FIGS. 27 and 28, all the ends 108 and 109 are bonded tothe suspension holder 17.

The above-described insulating film is manufactured of a material havinginsulation properties by using such a technique as application,electro-deposition, or deposition. As a material having insulatingproperties, insulating materials such as epoxy resin or inorganicinsulating materials such as silicon dioxide are used. Further, thesurfaces of the suspensions 18 a to 18 f having conductivity may besubjected to oxidation treatment in order to form an insulating film.Further, the suspensions 18 a to 18 f may be inserted into tube-shapedinsulating materials serving as insulating films, and metallic wire maybe threaded into resin wire by insert molding so as to be used as thesuspensions 18 a to 18 f.

As shown in FIGS. 29 and 30, the suspensions 18 a to 18 f are notprovided with an insulating film. However, the suspension holder 17 andthe bobbin receiving sections 96 and 97 can be formed of non-conductivematerials, and the lens holder 16 can be formed of the compositematerial. According to this construction, since the members to which thesuspensions 18 a to 18 f are attached have insulation properties, thesuspensions do not need to be subjected to insulation treatment. Thebobbin receiving sections 96 and 97 and the lens holder 16 areintegrally constructed by two-color molding, or the bobbin receivingsections 96 and 97 and the lens holder 16 are bonded to each other by anadhesive made of resin. In this embodiment, the suspensions 18 a to 18 fare not subjected to insulation treatment, but the lens holder 16 withhigh rigidity can be used.

Next, the construction of the lens holder 16 and the object lens 10 ofthe optical pickup device according to this embodiment will be describedin detail with reference to FIGS. 31 to 35. Further, members shown inFIGS. 31 to 35 have slight shapes from those shown in FIGS. 6, 7, and 25to 28. However, the members to which the same reference numerals areattached have the same functions.

FIG. 31 shows temperature distribution on the lens holder 16 when anelectric current flows in the focus coils 33 and 34, the tracking coils35 and 36, and the sub-tracking coils 37 and 38. The lens holder 16 hasthe object lenses 10 and 13 mounted thereon. The object lens 10 is usedfor long-wavelength laser, and the object lens 13 is used forshort-wavelength laser. FIG. 31 indicates in which position the objectlenses 10 and 13, the focus coils 33 and 34, the tracking coils 35 and36, and the sub-tracking coils 37 and 38 are respectively located. As anelectric current flows in the coils, heat is generated. The generatedheat moves to the lens holder 16 and then moves to the object lenses 10and 13. The object lenses 10 and 13 are deformed by the application ofheat. In general, the object lenses 10 and 13 are expanded, but can becontracted depending on a material. Further, resin is more severelydeformed by the application of heat than glass. As evident in FIG. 31, abias is present in the temperature distribution of the lens holder 16.In the object lens 10, the side of the set of the focus coil 33 and thesub-tracking coil 37 is more heated than the side of the tracking coil35. In the object lens 13, the side of the set of the focus coil 34 andthe sub-tracking coil 38 is more heated than the side of the trackingcoil 36. The bias of heat generates a bias in the deformation of thelens, thereby generating an aberration in light passing through theobject lenses 10 and 13.

In FIG. 32, reference numerals 110 a, 110 b, and 110 c represent objectlens support surfaces, and reference numerals 111 a, 111 b, 111 c, 113a, 113 b, and 113 c represent bonding sections. As described in FIG. 7,the object lens 13 for short-wavelength laser is brought down into thethrough-hole 16 b of the lens holder 16 from the direction P1 shown inFIG. 7 and is then fixed by a light-curing adhesive or the like.Further, the object lens 10 for long-wavelength laser is brought downinto the through-hole 16 a of the lens holder 16 from the direction P1shown in FIG. 7 and is then fixed by a light-curing adhesive or thelike. Between the object lenses 10 and 13 attached to the lens holder16, the object lens 10 is formed of glass or resin. In this embodiment,an object lens formed of glass is used as the object lens 10.Accordingly, since such a technique as metallic molding can be used, ahologram is easily provided in the object lens 10, and the sphericalaberration of light with plural kinds of wavelengths can be adjusted.The object lens 13 is formed of glass or resin (preferably,short-wavelength-light-resistant). In this embodiment, an object lensformed of glass is used as the object lens 13. Accordingly, the objectlens 13 is hardly degraded by short-wavelength light and can maintainexcellent optical characteristics. Further, although the object lenses10 and 13 are used in this embodiment, other condensing members such asa hologram and the like can be used.

As described in FIG. 6, reference numerals 33 and 34 represent focuscoils. The respective coils are wound in a ring shape and arerespectively provided in the diagonal positions of the lens holder 16.As the focus coils 33 and 34 are provided in both sides of the lensholder 16, it is possible to reduce the size of the optical pickupdevice, even though two of the object lenses 10 and 13 are mounted onthe lens holder 16. Reference numerals 35 and 36 represent trackingcoils. Similar to the focus coils 33 and 34, the tracking coils 35 and36 are wound in a ring shape and are respectively provided in thediagonal positions different from the focus coils 33 and 34. Between thefocus coils 33 and 34 and the lens holder 16, the sub-tracking coils 37and 38 are respectively provided. With the sub-tracking coils 37 and 38being provided, it is possible to suppress unnecessary inclination ofthe lens holder 16 which occurs on tracking.

Referring to FIG. 32, the relationship between the object lenses 10 and13 and the lens holder 16 will be described in detail. The object lens13 is brought down into the through-hole 16 b formed in a substantiallycircular shape from the near side of the drawing toward the far side andis then fixed to the lens holder 16 by a light-curing adhesive injectedinto the bonding sections 113 a, 113 b, and 113 c. Meanwhile, the objectlens 10 is brought down into the through-hole 16 a formed in asubstantially circular shape from the near side of the drawing towardthe far side. Adjusting is performed in a state where the object lens 10is supported by the object lens support surfaces 110 a, 110 b, and 110c. The object lens 10 is fixed to the lens holder 16 by a light-curingadhesive injected into the bonding sections 111 a, 111 b, and 111 c.Such a construction obtains optimal optical characteristics. As theadhesive, a light-curing adhesive such as ultraviolet curing adhesive isused, which is cured when ultraviolet rays are irradiated thereon. Aninstant adhesive or another adhesive can be used. Further, it ispreferable to use an adhesive with low heat conductivity. It is morepreferable to use an adhesive with heat insulating properties, in whichheat is not transmitted.

FIG. 33 shows a state where the object lenses 13 and 10 are brought downinto the through-hole 16 b and 16 a, respectively. As shown in FIG. 7,the outer circumferences of the object lenses 10 and 13 are abutted onthe circumferential edges of the through-holes 16 a and 16 b of the lensholder 16, respectively. The outer circumference of the object lens 10comes in contact with the circumferential edge of the through-hole 16 bof the lens holder 16 across the entire circumference. The abutmentbetween the object lens 10 formed of resin and the lens holder 16 willbe described in detail.

FIG. 34 is a sectional view taken along A-A line of FIG. 33, and FIG. 35is a sectional view taken along B-B line of FIG. 33.

Reference numeral 10 a represents an object lens circumferential sectionwhich is the edge of the object lens 10. A portion of the object lenscircumferential section 10 a is abutted on the lens holder 16, and theobject lens 10 is bonded to the lens holder 16. Then, the lens holder 16and the object lens 10 are fixed to each other. Reference numeral 10 brepresents an object lens lower surface where the light emitted from thelong wavelength optical unit 3 is incident on the object lens 10, andreference numeral 10 c represents an object lens upper surface fromwhich the light incident on the object lens 10 from the object lenslower surface 10 b is emitted. The light, passing through the objectlens 10 so as to be emitted from the object lens upper surface 10 c, iscondensed into the optical disk 2 facing the object lens upper surface10 c. The object lens lower surface 10 b is provided with a hologram. Alight flux (red: corresponding to DVD) with a wavelength of about 660 nmor a light flux (infrared: corresponding to CD) with a wavelength ofabout 780 nm, which is emitted from the long wavelength optical unit 3and passes through the relay lens 6 or the collimator lens 8 so as to beparallel light, passes through the hologram such that the sphericalaberration thereof is adjusted.

Reference numeral 110 represents an object lens support surface providedin the lens holder 16. Since FIG. 34 is a sectional view taken along A-Aline of FIG. 33, the object lens support surface 110 becomes the objectlens support surface 110 c, strictly speaking. However, the object lenssupport surfaces 110 a, 110 b, and 110 c have the same construction andfunction. Therefore, the object lens support surfaces 110 a, 110 b, and110 c are collectively referred to as the object lens support surface110. The object lens support surface 110 has an inclined surface whichis directed from a lens holder upper surface 16 c of the lens holder 16toward the through-hole 16 a. The inclined surface is a substantiallyspherical surface which is concaved with respect to the lens holderupper surface 16 c. When the object lens 10 is placed on the object lenssupport surface 110, it is preferable that the principal point of theobject lens 10 coincides with the center of the substantially sphericalsurface of the object lens support surface 110. It is also consideredthat the principal point of the object lens 10 is slightly deviated fromthe center of the substantially spherical surface of the object lenssupport surface 110. However, a certain deviation is allowed. With thesubstantially spherical surface being provided in the object lenssupport surface 110, it is possible to adjust a direction of the opticalaxis of the object lens 10.

Reference numeral 111 represents a bonding section provided in the lensholder 16. Since FIG. 35 is a sectional view taken along B-B line ofFIG. 33, the bonding section 111 is the bonding section 111 b, strictlyspeaking. However, the bonding sections 111 a, 111 b, and 111 c have thesame construction and function. Therefore, the bonding sections 111 a,111 b, and 111 c are collectively referred to as the bonding section111. The bonding section 111 becomes a stepped-down portion which ismore stepped down toward the through-hole 16 a than the lens holderupper surface 16 c of the lens holder 16. The bonding section 111 isconstructed so as not to be struck by the object lens 10 when tilting isadjusted while the object lens 10 is slidably moved on the object lenssupport surface 110.

The disposition of the object lens support surface 110 and the bondingsection 111 will be described. As shown in FIG. 32, an angle which isoccupied by each of the object lens support surfaces 110 a, 110 b, and110 c in the circumferential edge of the through-hole 16 a is about 15degrees, and an angle which is occupied by each of the bonding sections111 a, 111 b, and 111 c in the circumferential edge of the through-hole16 a is about 25 degrees, when the circumferential edge of thethrough-hole 16 a is seen from the central axis of the through-hole 16a. The contact portion between the object lens support surface 110 andthe bonding section 111, that is, the contact portion between the lensholder 16 and the object lens 10 is reduced. Therefore, a flow path ofheat from the lens holder 16 to the object lens 10 is narrowed, so thatan increase in temperature of the object lens 10 can be suppressed andthe deformation of the object lens 10 can be reduced.

The bonding section 111 a is disposed away from the vicinities of theset of the focus coil 33 and the sub-tracking coil 37 and in a positionwhich is not too close to the tracking coil 35. In other words, thebonding section 111 a is disposed in a position which is closer to thetracking coil 35 than the set of the focus coil 33 and the sub-trackingcoil 37. Then, when an electric current flows in the focus coils 33 and34, the tracking coils 35 and 36, and sub-tracking coils 37 and 38 so asto drive the lens holder 16, the bonding section 111 a can be disposedin a position, where the temperature is low, between the tracking coil35 and the set of the focus coil 33 and the sub-tracking coil 37. Thefocus coil 33 and the sub-tracking coil 37 are where the temperatureeasily increases, and the tracking coil 35 is where an increase intemperature is smaller than the focus coil 33 and the sub-tracking coil37. The bonding sections 111 b and 111 c are disposed in a position ofwhich the temperature is almost the same as the position of the bondingsection 111 a on the lens holder 16. Preferably, a difference intemperature among the bonding sections 111 a, 111 b, and 111 c is in therange of 1 to 2 degrees. Since the bonding sections 111 a, 111 b, and111 c are constructed to have the substantially same size, the adhesivesinjected into the respective bonding sections 111 come in contact withthe object lens 10 at the same area. Accordingly, an amount of heat,which flows in the object lens 10 from the bonding sections 111 a, 111b, and 111 c provided in the positions where the temperature issubstantially identical, becomes substantially uniform, and a bias ishardly generated in the deformation of the object lens 10. Therefore, itis possible to suppress astigmatism of light from occurring, the lightpassing through the object lens 10. Further, the bonding sections 111 a,111 b, and 111 c are disposed at even angles around the central axis ofthe through-hole 16 a so as to be close to each other at an interval of120 degrees. Preferably, the bonding sections 111 are disposed at every120 degree at constant intervals (at the same angle). However, thebonding sections 111 are disposed in the positions, of which thetemperatures at the time of driving become equal, around thethrough-hole 16 a such that intervals therebetween are as approximate aspossible. Accordingly, even though an adhesive injected into the bondingsections 111 is contracted when hardening, a force which pulls theobject lens 10 from the lens holder 16 is reduced, so that thepositioned object lens 10 is hardly shifted.

Although the bonding sections 111 are composed of three sections in thisembodiment, the number of the bonding sections 111 is not limitedthereto. For example, when the bonding sections 111 are composed of twosections, the bonding sections 111 are disposed around the central axisof the through-hole 16 a at an interval of 180 degrees. When the bondingsections 111 are composed of four sections, the bonding sections 111 aredisposed around the central axis of the through-hole 16 a at an intervalof 90 degrees. As such, even when the number of the bonding sections 111is varied, it is preferable that the bonding sections 111 are disposedaround the central axis of the through-hole 16 a at even angles.However, if the number of the bonding sections 111 decreases, a forcefor fixing the object lens 10 to the lens holder 16 is weakened, or thebonding sections need to be widened in order to prevent the force frombeing weakened. Further, if the number of the bonding sections 111increases, the respective bonding sections 111 can be constructed to besmall. However, a large number of positions where the temperature issubstantially identical are needed on the lens holder 16, and the numberof places into which an adhesive should be injected increases so thatthe number of assembling processes increases. Therefore, it ispreferable that the bonding sections 111 are composed of three sections.

In this embodiment, the bonding sections 111 a, 111 b, and 111 c areconstructed to have the same area and are disposed in positions wherethe temperatures are approximate to each other on the lens holder 16.However, the areas of the bonding sections 111 are varied by thefollowing method. The area of the bonding section 111, provided in aplace where the temperature is high on the lens holder 16, is reduced,and the area of the bonding section 111, provided in a place where thetemperature is low on the lens holder 16, is enlarged. Then, an amountof heat which flows from each of the bonding sections 111 can beuniformized.

The object lens support surfaces 110 a and 110 b are adjacent to thebonding sections 111 a and 111 b, respectively, and are provided inpositions closer to the set of the focus coil 33 and the sub-trackingcoil 37 than the bonding sections 111 a and 111 b. Further, the objectlens support surface 110 c is adjacent to the bonding section 111 c andis provided in a position closer to the tracking coil 35 than thebonding section 111 c. As the object lens support surfaces 110 areprovided adjacent to the bonding sections 111, the object lens supportsurfaces 110 are disposed in positions where the temperature is low onthe lens holder 16, which makes it possible to suppress heat from beingtransmitted to the object lens 10. Further, as the object lens supportsurfaces 110 are provided adjacent to the bonding sections 111, theobject lens support surfaces 110 are also disposed around the centralaxis of the through-hole 16 a at even intervals. Such a constructionallows the object lens 10 to be stably supported by the object lenssupport surfaces 110.

In this embodiment, the object lens support surfaces 110 supporting theobject lens 10 are composed of three of the object lens support surfaces110 a, 110 b, and 110 c. In such a construction, the lens holder 16comes in contact with the object lens circumferential section 10 a atthree points, so that the surface of the object lens 10 to be supportedcan be determined uniquely. Although the object lens support surfaces110 are composed of three surfaces in this embodiment, the number ofpoints supporting the object lens 10 is not limited thereto.

In this embodiment, the object lens support surface 110 and the bondingsurface 111 are provided as different surfaces on the lens holder 16. Insuch a construction, an adhesive is prevented from being adhered on theobject lens support surfaces 110 for pitching adjustment, and the objectlens 10 can be adjusted with high precision. Further, the bondingsections 111 are provided separately from the object lens supportsurfaces 110 so as to perform bonding between the object lens 10 and thelens holder 16. Therefore, the object lens 10 and the lens holder 16 canbe fixed robustly to each other.

The object lens support surfaces 110 a and 110 b, respectively, areprovided in positions closer to the set of the focus coil 33 and thesub-tracking coil 37 than the bonding sections 111 a and 111 b, and theobject lens support surface 110 c is provided in a position closer tothe tracking coil 35 than the bonding section 111 c. However, the objectlens 10 and the lens holder 16 come in contact with only the object lenssupport surfaces 110, and the bonding sections 111 to which heat iseasily transmitted can be disposed in positions separated fromhigh-temperature portions. Therefore, it is possible to suppress theobject lens 10 from increasing in temperature.

In this embodiment, it is preferable that the entire portion or at leasta portion of the lens holder 16 is also formed of a material (compositematerial) in which fiber is dispersed in resin, as described in FIGS. 25and 30. As for resin, liquid crystal polymer, epoxy resin,polyimide-based resin, polyamide-based resin, acrylic resin or the likeis preferably used. As for fiber, carbon fiber, carbon black, metallicfiber such as copper, nickel, aluminum, or stainless steel, or compositefiber therefrom is preferably used. As such, when the lens holder 16 isformed of the composite material, the lens holder 16 has conductivity.However, the rigidity of the lens holder 16 increases, and the resonancefrequency increases. Therefore, at least one of recording andreproducing can be performed on the optical disk 2 at high double speed.In this embodiment, the lens holder 16 is formed of a material in whichcarbon fiber is dispersed in liquid crystal polymer. It is consideredthat such a construction increases the heat conductivity of the lensholder 6. If the heat conductivity increases, the temperature of thelens holder 16 is easily equalized, and the positions of the bondingsections 111 can be selected from a wide range and can be easilydisposed around the through-hole 16 a at even angles (about 120 degrees,when three of the bonding sections 111 are provided).

Next, the light receiving section 1 b of the short wavelength opticalunit 1 will be described in detail with reference to FIGS. 36 to 49.Further, members shown in FIGS. 36 to 49 have a slightly different shapefrom the members shown in FIGS. 9 and 10. However, the members have thesame functions.

FIG. 36 is perspective view illustrating a light receiving element 114composing the light receiving section 1 b, seen from the surface of anintegrated circuit (IC).

In FIG. 36, reference numeral 114 represents a light receiving elementcomposed of a bare chip IC which converts reflected light from theinformation recording surface of an optical disk into an electricalsignal. In the light receiving element 114, reference numeral 114 arepresents a light detecting section which is disposed in the center ofthe light receiving element 114 so as to detect light incident on thelight receiving element 114, 114 b represents an electrical circuitsection, 114 c represents an electrode pad for inputting and outputtingan electrical signal, and 114 d represents a bump formed of gold orsolder, which is provided on the electrode pad 114 c so as to secureelectrical connection. When the electrical connection between theelectrode pad 114 c and an electrode pad section 116 on theflexible-printed board 49 can be reliably secured by an adhesive resinlayer 115 for fixing a light receiving element to be described below,the bump 114 d may be omitted. In the light receiving element 114, thesurface having the light detecting section 114 a and the electrode pad114 c is referred to as a light detecting surface.

FIG. 37 is a perspective and exploded view illustrating constituentparts of a flexible printed board unit 121 in order to explain theconstruction and assembling method thereof.

In FIG. 37, reference numeral 49 represents the flexible printed boardwhich is an electrical wiring board having flexibility, referencenumeral 114 represents a light receiving element (the electrode surfacethereof is not shown) explained in FIG. 36, reference numeral 115represents an adhesive resin layer for fixing a light receiving elementwhich is an anisotropic conductive film (ACF) for protecting theconnection between electrodes and fixing the flexible printed board 49and the light receiving element 114, reference numeral 116 representselectrode pad sections which are arranged in two lines on the flexibleprinted board 49 at the same intervals as those between the electrodepads 114 c, reference numeral 118 represents a transparent glasssubstrate which protects the electrode pads 114 c of the light receivingelement 114 and through which reflected light from the disk passes,reference numeral 117 represents an adhesive for bonding the flexibleprinted board 49 and the transparent glass substrate 118, referencenumeral 119 represents an electrode pattern formed on the end portion ofthe flexible printed board 49, reference numeral 120 represents adecoupling capacitor between power source grounds, the decouplingcapacitor improving electrical characteristics of the light receivingelement 114, and reference numeral 49 a represents a through-hole whichis provided in the substantial center between two lines of the electrodepad sections 116 and through which reflected light from the optical diskpasses. As the flexible printed board 49, a single-sided board is usedin order to realize ease in manufacture and reduce a manufacturing cost.The single-sided board has wiring lines and electrode pads formed ononly one side. However, a double-sided board may be used, which haswiring lines and electrode pads formed on both sides. In the lightreceiving element 114, the surface on which the wiring lines andelectrode pads are formed is referred to as an electrode surface.

In FIG. 37, the through-hole 49 a having a substantially rectangularshape is provided. Therefore, when the flexible printed board 49 and thelight receiving element 114 are bonded to each other, at least a portionof the electrode pad 114 c for inputting and outputting an electricalsignal is seen from the through-hole 49 a, and the reflected light fromthe information recording surface of the optical disk, which has passedthrough the transparent glass substrate 118, reaches the light detectingsection 114 a of the light receiving element 114. However, thethrough-hole 49 a may be formed in a diamond shape shown in FIG. 38, atriangle shape, or a star shape. Alternately, the through-hole 49 a maybe formed in an elliptical or circular shape shown in FIG. 39. Further,in such a construction where the reflected light from the informationrecording surface of the optical disk, which has passed through thetransparent glass substrate 118, reaches the light detecting section 114a of the light receiving element 114, a plurality of through-holes 49 acan be provided, as shown in FIG. 40.

As the through-hole 49 a is provided in the flexible printed board 49,that is, as the through-hole 49 a through which the reflected light fromthe optical disk passes is constructed to be surrounded by the flexibleprinted board 49, the distance between two lines of the electrode padsections 116 arranged in two lines hardly changes even in the flexibleprinted board formed of a flexible material. Further, the electrode pads114 a of the light receiving element 114 and the electrode pad sections116 of the flexible printed board 49 can be reliably connected to eachother.

In FIG. 37, the through-hole 115 a having a substantially rectangularshape is provided in the center of the adhesive resin layer 115 forfixing a light receiving element. However, if the adhesive resin layer115 is provided at least between the electrode pads 114 c of the lightreceiving element 114 and the electrode pad sections 116 of the flexibleprinted board 49, the adhesive resin layer 115 may be composed of twopieces of small adhesive resin layers, as shown in FIG. 41. In such aconstruction, the through-hole 115 a does not need to be provided in theadhesive resin layer 115, and the used amount of adhesive resin layer115 can be reduced.

As a wiring board, the flexible printed board 49 is preferably used.Further, other wiring boards such as a glass epoxy board, a ceramicboard and the like can be used. However, when the flexible printed board49 is used, it is possible to construct a light and slim optical pickupdevice.

As shown in FIG. 37, the light receiving element 114 and the flexibleprinted board 49 is fixed to each other by so-called flip-chip mounting,in which the light receiving element 114 having the bumps 114 d formedthereon is fixed to the electrode pad sections 116 by pressing andheating, with the adhesive resin layer 115 interposed therebetween. Asthe adhesive resin layer 115, an anisotropic conductive film (ACF) ispreferably used. However, the adhesive resin layer 115 is not limitedthereto.

Further, the transparent glass substrate 118 is fixed to the rearsurface of the flexible printed board 49, having the light receivingelement 114 mounted thereon, by pressing and heating with the adhesive117 interposed therebetween. Further, the through-hole 49 a passing thereflected light from the optical disk is provided in the substantialcenter between the lines of the electrode pads 114 c arranged in twolines on the flexible printed board 49, so that the reflected light fromthe optical disk, which is incident from the side of the transparentglass substrate 118, can reach the light detecting section 114 a withinthe light receiving element 114. In such a construction, the lightdetecting section 114 a within the light receiving element 114 can behermetically sealed, and the protection of connection between the lightreceiving element 114 and the electrodes and the fixing between theparts can be secured.

In the above descriptions, the through-hole 49 a is provided in theflexible printed board 49. However, if the reflected light from theinformation recording surface of the optical disk, which has passedthrough the transparent glass substrate 118, can reach the lightdetecting section 114 a of the light receiving element 114, a notchedportion 49 b shown in FIG. 42 can be provided in the flexible printedboard 49. The notched portion 49 b can be provided by a pressing processafter the flexible printed board 49 is formed, or can be provided whenthe outer shape of the flexible printed board 49 is formed.

Similarly, if the reflected light from the information recording surfaceof the optical disk, which has passed through the transparent glasssubstrate 118, can reach the light detecting section 114 a of the lightreceiving element 114, a window portion 49 c may be provided, the windowportion 49 c being combined with the flexible printed board 49. Thewindow portion 49 c is a transparent glass member. In FIG. 43, thewindow portion 49 c is formed in such a shape that a transparent glassmember is assembled into the through-hole 49 a which has been explainedusing FIG. 37. However, the window portion 49 c may be formed in such ashape that a transparent glass member is assembled into the through-hole49 a or the notched portion 49 b or may be formed in another shape.Since the window portion 49 c is not degraded by the transmission ofshort-wavelength laser, the reflected light from the informationrecording surface of the optical disk can be effectively guided to thelight detecting section 114 a of the light receiving element 114.Further, when the window portion 49 c is provided in the flexibleprinted board 49, it is also considered that the light receiving section1 b of the short wavelength optical unit 1 is constructed without thetransparent glass substrate 118.

FIG. 44 is a perspective view of a flexible printed board unit 121constructed and assembled as described above.

As such, the light receiving element 114 composed of a bare chip IC ismounted on the flexible printed board 49 by using flip-chip mounting,thereby constructing a light receiving unit 123. Then, a photoelectricconversion integrated circuit device of a package which is sealed by alid made of glass does not need to be manufactured, and the lightreceiving section 1 b corresponding to short-wavelength laser can beconstructed at a low cost. Further, the light receiving element 114composed of a bare chip IC is mounted on the flexible printed board 49as it is. Therefore, it is possible to achieve the miniaturization ofthe optical pickup device.

FIG. 45 is a perspective view showing a state where the flexible printedboard unit 121 shown in FIG. 44 is bent. The decoupling capacitor 120between power source grounds is soldered on the surface of the flexibleprinted board 49 and is then folded so as to face the rear surface ofthe surface having the light detecting section 114 a of the lightreceiving element 114.

FIG. 46 is a perspective view of the light receiving unit 123. Referencenumeral 122 represents a flexible printed board housing part whichhouses and holds the flexible printed board unit 121. The bent flexibleprinted board unit 121 shown in FIG. 45 is fixed to the flexible printedboard housing part 122 by using a light-curing adhesive. As theadhesive, a light-curing adhesive such as ultraviolet curing adhesive isused, which is cured when ultraviolet rays are irradiated thereon.However, an instant adhesive or another adhesive may be used. Further,the flexible printed board unit housing part 122 is formed of metal orresin. Preferably, metal is used.

FIG. 47 is a diagram illustrating the short wavelength optical unit 1using the light receiving unit 123 serving as the light receivingsection 1 b. Reference numeral 1 c represent a light receiving sectionwhich is provided so as to monitor an amount of light emitted from thelight source section 1 a (not shown) of the short wavelength opticalunit 1. After relative positions with respect to the wave length opticalunit 1 are fine-adjusted, the light receiving unit 123 and the lightreceiving section 1 c are fixed to the short wavelength optical unit 1and are then embedded in the base 15, as shown in FIG. 48. The lightreceiving unit 123 is fixed to the loading section 43 of the shortwavelength optical unit 1 by using a light-curing adhesive, after theflexible printed board unit housing part 122 is fine-adjusted withrespect to the short wavelength optical unit 1 in a state where it isheld by a jig. As the adhesive, a light-curing adhesive such asultraviolet curing adhesive is also used, which is cured whenultraviolet rays are irradiated thereon. However, an instant adhesive oranother adhesive may be used.

In the light receiving unit 123, the flexible printed board unit 121 ishoused and held by the flexible printed board unit housing part 122which is more robust than the flexible printed board unit 121.Therefore, the fine adjustment of the relative position with respect tothe short wavelength optical unit 1 can be smoothly performed.

Here, an operation will be simply described with reference to FIG. 48,focusing on a recoding information reproducing function of the opticalpickup device.

Inside the optical pickup device shown in FIG. 48, laser light (outwardlight) for recording information reproduction, irradiated by the shortwavelength optical unit 1, is focused on the information recordingsurface of the optical disk (not shown) through a plurality of opticalelements (not shown) by the object lens 13.

The light (inward light) reflected by the information recording surfaceof the optical disk follows the same light path as the outward lightimmediately before the inward light reaches the beam splitter (notshown) inside the short wavelength optical unit 1. Then, the light isturned in the direction of the light receiving unit 123 by the operationof the beam splitter.

Next, other components of the light receiving unit 123 serving as thelight receiving section 1 b will be shown with reference to FIG. 49.

The construction of the light receiving element 123 shown in FIG. 49 isthe same as that of the light receiving unit 123 described by referringto FIGS. 37 to 48, except that the flexible printed board unit housingpart 122 for housing the flexible printed board unit 121 is not providedand the light receiving section attaching portion 48 is provided betweenthe flexible printed board 49 and the transparent glass substrate 118.The light receiving section attaching portion 48 is provided separatelyfrom the loading section 43 so as to fix the flexible printed board 49and the light receiving element 114 to the short wavelength optical unit1, the light receiving element 114 being fixed to the flexible printedboard 49. Preferably, the loading section 43 is formed of a metallicmaterial such as zinc die-cast. In the light receiving element 114composed of a bare chip IC, the light detecting section 114 a fordetecting laser light is directed toward the flexible printed board 49having the through-hole 49 a. The light receiving element 114 and theflexible printed board 49 are bonded to each other by pressing andheating, with the adhesive resin layer 115 for fixing a light receivingelement interposed therebetween. The adhesive resin layer 115 is formedof an anisotropic conductive film (ACF). The light receiving sectionattaching portion 48 is disposed in the side opposite to the side of theflexible printed board 49 where the light receiving element 114 isfixed. The light receiving section attaching portion 48 is formed of ametallic plate and has the through-hole 45 provided in the centerthereof. The light receiving section attaching portion 48 is bonded tothe flexible printed board 49 by using the adhesive 117 which is anorganic adhesive such as a heat-curing adhesive. The transparent glasssubstrate 118 is disposed in the side of the light receiving sectionattaching portion 48 opposite to the flexible printed board 49 so as toblock the through-hole 45 of the light receiving section attachingportion 48. The transparent glass substrate 118 is bonded by theadhesive 126 such as a light-curing adhesive. The light receiving unit123 constructed in such a manner is fixed to the loading section 43 ofthe short wavelength optical unit 1 by a light-curing adhesive or thelike, after the position thereof is fine-adjusted with respect to theshort wavelength optical unit 1.

Preferably, the light receiving section attaching portion 48 is formedof a metallic material such as zinc die-cast. As the light receivingsection attaching portion 48 is formed of a metallic material such aszinc die-cast, the position of the light detecting section 114 a of thelight receiving unit 123 can be reliably fine-adjusted with respect tothe short wavelength optical unit 1, and the loading section 43 formedof a metallic material can be easily fixed by the adhesive 127 or thelike. As the adhesive 127, a light-curing adhesive such as ultravioletcuring adhesive is used, which cures when ultraviolet rays areirradiated thereon. Then, the loading section 43, of which the positionhas been fine-adjusted, and the light receiving unit 123 can be easilybonded to each other.

As described by referring to FIGS. 36 to 49, resin is not present in thepath to the light emitting element of the reflected light from theoptical disk. Therefore, even in the optical disk drive usingshort-wavelength laser, which is considered to be the mainstream in thefuture, the light receiving section 1 b is suppressed from beingdegraded by the passing of laser, so that high-efficiency lightdetection can be performed.

In the light receiving section 1 b, the electrode of the light receivingelement 114 composed of a bare chip IC is directly connected to theelectrode pad section 116 on the flexible printed board 49. Therefore,the dimension of the light receiving unit in the thickness direction ofthe optical pickup device can be reduced so that the optical disk drivecan be reduced in size.

In the above descriptions, the flexible printed board 49 is providedbetween the light receiving element 114 and the transparent glasssubstrate 118 in the light receiving section 1 b of the short wavelengthoptical unit 1, and the light receiving section 1 b and the transparentglass substrate 118 are disposed to face each other through thethrough-hole 45 of the flexible printed board 49. However, as the lightreceiving section 1 c of the short wavelength optical unit 1 isconstructed in the same manner, the light receiving section 1 b issuppressed from being degraded by the passing of short-wavelength lasersuch that light detection can be effectively performed. The lightreceiving sections 3 b and 3 c of the long wavelength optical unit 3 canbe constructed in the same manner.

Hereinafter, the light receiving section 3 b of the long wavelengthoptical unit 3 will be described with reference to FIG. 50. Moreover,members to which the same reference numerals as those shown in FIGS. 36to 49 are attached have the same functions, FIGS. 36 to 49 describingthe light receiving section 1 b of the shot wavelength optical unit 1.In FIG. 50, the members correspond to long-wavelength laser.

In FIG. 50, reference numeral 49 d represents a transparent boardsection formed of transparent resin in the flexible printed board 49.The reflected light from the information recording surface of theoptical disk is transmitted through the transparent glass substrate 118and is then transmitted through the transparent board section 49 d so asto reach the light detecting section 114 a of the light receivingelement 114. The transparent board section 49 d may be such a memberthat a portion corresponding to the through-hole 49 a or the notchedportion 49 b is constructed by using a transparent resin member.Alternately, the transparent board section 49 d may be formed in anothershape. With the transparent board section 49 d being provided in theflexible printed board 49, the reflected light from the informationrecording surface of the optical disk can be effectively guided to thelight detecting section 114 a of the light receiving section 114, eventhough the through-hole 49 a or the notched portion 49 b is notprovided. Further, when the transparent board section 49 d is providedin the flexible printed board 49, it is also considered that the lightreceiving section 3 b of the long wavelength optical unit 3 isconstructed without the transparent glass substrate 118. Further, thetransparent board section 49 d serving as a light transmitting sectionof the flexible printed board 49 may be formed of an opaque member, ifthe member can effectively transmit light. Further, the transparentboard section 49 d may be formed of another member except for resin.

In FIG. 50, the transparent board section 49 d is provided in theflexible printed board 49. However, if the flexible printed board 49itself is formed of transparent resin, the flexible printed board 49 maybe constructed without the transparent board section 49 d.

As described above, the light receiving section 3 c can be constructedin the same manner as the light receiving section 3 b of the longwavelength optical unit 3.

The light transmitting sections such as the transparent glass substrate118 and the window portion 49 c formed of transparent glass can beformed of an opaque member or another member except for glass, if themember can effectively transmit light.

As described with reference to FIGS. 36 to 50, the transparent glasssubstrate 118 is fixed to the rear surface of the flexible printed board49 having the light receiving element 114 mounted thereon by pressingand heating, with the adhesive 117 interposed therebetween. Further, thelight transmitting section is provided in the center between two linesof the electrode pad sections 116 arranged in two lines on the flexibleprinted board 49, and the light receiving unit 123 is constructed inwhich the reflected light from the optical disk, incident from the sideof the transparent glass substrate 118, reaches the light detectingsection 114 a within the light receiving element 114. Therefore, thelight receiving section can be constructed at a low cost, and thedimension thereof in the thickness direction of the optical pickupdevice can be reduced.

Next, the construction of the magnets 39 to 42 of the optical pickupdevice will be described in detail with reference to FIGS. 51 to 53.Further, members shown in FIGS. 51 to 53 have a slightly different shapefrom the members shown in FIGS. 6 to 7. However, the members to whichthe same reference numerals are attached have the same functions.

First, the suspensions 18 will be described with reference to FIG. 51.FIG. 51A is a diagram illustrating the optical pickup device accordingto this embodiment, and FIG. 51B is a sectional view taken along A-Aline of FIG. 51A. In FIG. 51B, the suspensions 18 d, 18 e, and 18 f areshown for description. FIG. 51B shows a positional relationship amongthe optical disk 2, the lens holder 16, the suspension holder 17, thesuspensions 18 d, 18 e, and 18 f, the focus coils 33 and 34, thetracking coils 37 and 38, and the magnets 39 and 42, when an electriccurrent does not flow in the focus coils 33 and 34, the tracking coils35 and 36, and the sub-tracking coils 37 and 38, that is, when the lensholder 16 is not driven.

In FIG. 51B, descriptions will be made by attaching reference numeral tothe suspension 18 d. However, as the suspensions 18 f and 18 e are alsosuspended substantially parallel to the suspension 18 d between the lensholder 16 and the suspension holder 17, the same effect can be obtained.The suspensions 18 a, 18 b, and 18 c, which are positioned in the sideof the lens holder 16 opposite to the suspensions 18 d, 18 e, and 18 fand are not shown in FIG. 51B, have the same effect. Hereinafter, thesuspensions 18 a, 18 b, 18 c, 18 d, 18 e, and 18 f are collectivelyreferred to as the suspensions 18.

In FIGS. 51A and 51B, reference numeral 1816 represents a couplingportion in which the suspension 18 is coupled to the lens holder 16, andreference numeral 1817 represents a coupling portion in which thesuspension 18 is coupled to the suspension holder 17. The suspension 18is elastically deformed more in the side of the suspension holder 17than in the coupling portion 1816 and more in the side of the lensholder 16 than in coupling portion 1817, that is, between the couplingportion 1816 and the coupling portion 1817. Then, the suspension 18moves the lens holder 16 in the height direction and the width directionshown in FIGS. 51A and 51B, respectively.

As shown in FIG. 51B, the coupling portion 1816 between the suspension18 and the lens holder 16 is positioned closer to the object lenses 10and 13 than the coupling portion 1817 between the suspension 18 and thesuspension holder 17. Here, the side of the object lenses 10 and 13serving as condensing members in the optical pickup device according tothis embodiment indicates a direction where short-wavelength laser orlong-wavelength laser, emitted from the short wavelength optical unit 1or the long wavelength optical unit 3 so as to pass through the beamsplitter 7, the collimator lens 8 or the like, is emitted toward theoptical disk 2 from the object lenses 10 and 13. Next, the relationshipwith the optical disk 2 will be described.

Reference numerals d1816 and d1817, respectively, represent distancesbetween the coupling portions 1816 and 1817 and the surface of theoptical disk 2 on which information is recoded, the optical disk 2 beingmounted on the spindle motor 25. As shown in FIG. 51B, the relationshipbetween the distances d1816 and d1817 when the lens holder 16 is notdriven is as follows: distance d1816<distance d1817. That is, thesuspension 18 is supported obliquely in a direction approaching theoptical disk 2 by the suspension holder 17 so as to elastically supportthe lens holder 16. In other words, the coupling portion 1817 betweenthe suspension 18 and the suspension holder 17 is closer to the opticaldisk 2 than the coupling portion 1816 between the suspension 18 and thelens holder 16.

In such a construction, the suspension holder 17 and the suspensions 18are supported in the position separated from the optical disk 2.Therefore, the suspension holder 17 itself can be constructed in a lowlevel in the optical pickup device, which makes it possible to achievethe miniaturization of the optical disk drive.

Next, the magnets 39 to 42 will be described with reference to FIGS. 52Aand 52B. FIG. 52B is a sectional view taken along A-A line of FIG. 51A.

In FIGS. 52A and 52B, the magnets 39 and 42, respectively, are focusmagnets which drive the lens holder 16 in the height direction shown inFIG. 52B, and the magnets 40 and 41, respectively, are tracking magnetswhich drive the lens holder 16 in the width direction shown in FIG. 52A.The magnets 39 to 42 are magnetized and disposed as described byreferring to FIGS. 6 to 8. As in FIGS. 6 and 7, the magnet 42 serving asa focus magnet is disposed between the lens holder 16 and the suspensionholder 17, and the magnet 39 serving as a focus magnet is disposed inthe opposite side to the magnet 42 by reference to the lens holder 16.Further, the magnet 41 serving as a tracking magnet is disposed betweenthe lens holder 16 and the suspension holder 17, and the magnet 40serving as a tracking magnet is disposed in the opposite side to themagnet 41 by reference to the lens holder 16. Further, the magnets 39and 42 are disposed in diagonal positions of the lens holder 16, and themagnets 40 and 41 are disposed in the other diagonal positions of thelens holder 16. The ends of the magnets 39 to 42 in the height directionwhich are opposite to the ends thereof at the optical disk 2, that is,the lower ends of the magnets 39 to 42, respectively, are positioned onthe same plane. Further, the magnets 39 to 42 are disposed so that thelong sides thereof, respectively, are substantially perpendicular to thesurface of the optical disk 2 on which information is recorded, theoptical disk 2 being mounted on the spindle motor 25.

In FIG. 6, each of the magnets 40 and 41 is composed of one magnet. Asshown in FIG. 52A, however, each of the magnets 40 and 41 can becomposed of two magnets. The magnet 40 is disposed so that the N-pole ofone magnet and the S-pole of the other magnet are exposed so as to facethe tracking coil 35. In the width direction, the magnets are disposedso that the magnetic poles can be exposed to the surface facing thetracking coil 35 in an order of the N-pole and the S-pole from thecenter surface (the cross-section taken along A-A line of FIG. 6)between the suspensions 18 a, 18 b, and 18 c and the suspensions 18 d,18 e, and 18 f toward the suspensions 18 a, 18 b, and 18 c. The magnet41 is disposed so that the N-pole of one magnet and the S-pole of theother magnet are exposed so as to face the tracking coil 36. In thewidth direction, the magnets can be disposed so that the magnetic polesare exposed to the surface facing the tracking coil 36 in an order ofthe N-pole and the S-pole from the center surface (the cross-sectiontaken along A-A line of FIG. 6) between the suspensions 18 a, 18 b, and18 c and the suspensions 18 d, 18 e, and 18 f toward the suspensions 18d, 18 e, and 18 f.

In such a construction, the magnet pole disposition described in FIG. 6can be achieved. Further, when each of the magnets is composed of onemagnet as described in FIG. 6, portions of the magnets 40 and 41, whichare not magnetized because the orientations of magnet poles of themagnets 40 and 41 are switched, can be reduced, and the operationsensitivity of the lens holder 16 in the width direction can beincreased.

Referring to FIG. 52B, the magnets 39 and 42 serving as focus magnets,which drive the lens holder 16 in the height direction, will bedescribed in detail.

As shown in FIG. 52B, the magnet 39 disposed in the opposite side to thelens holder 16 is constructed so as to project toward the object lenses10 and 13 more than the magnet 42 disposed between the lens holder 16and the suspension holder 17. Hereinafter, the descriptions will be madeby using the relationship with the optical disk 2.

In FIG. 52B, reference numerals 139 and 142, respectively, represent thelengths of the magnets 39 and 42 in the height direction, that is, thelengths of the long sides of the magnets 39 and 42. Reference numeralsd39 and d42, respectively, represents distances from the surface of theoptical disk 2, on which information is recorded, to the magnets 39 and42 in a state where the optical disk 2 is mounted on the spindle motor25.

The relationship between the lengths of the magnets 39 and 42 is asfollows: length 139>length 142. That is, the magnet 42 is shorter thanthe magnet 39. The relationship among the dimensions d39, d42, 139, and142 related to the magnets 39 and 42 is expressed by the followingequation: d39+139≈d42+142. That is, the distance from the optical disk 2to the lower end of the magnet 39 is substantially equal to the distancefrom the optical disk 2 to the lower end of the magnet 42. In otherwords, the distance from the surface of the optical disk 2 on whichinformation is recorded to the end of the magnet 39 in the heightdirection which is opposite to the end thereof at the optical disk 2 issubstantially equal to the distance from the surface of the optical disk2 on which information is recorded to the end of the magnet 42 in theheight direction which is opposite to the end thereof at the opticaldisk 2, in a state where the optical disk 2 is mounted on the spindlemotor 25. Accordingly, the relationship between the distance d39 betweenthe optical disk 2 and the magnet 39 and the distance d42 between theoptical disk 2 and the magnet 42 is as follows: d39<d42. That is, thedistance from the optical disk 2 to the end of the magnet 42 in theheight direction at the optical disk 2 is larger than the distance fromthe optical disk 2 to the end of the magnet 39 at the optical disk 2.

Further, the distance from the extending surface of an optical-diskmounting surface of the spindle motor 25, on which the optical disk 2 ismounted, to the end of the magnet 42 in the height direction at theoptical disk 2 is larger than the distance from the extending surface tothe end of the magnet 39 at the optical disk 2.

Further, as for the distance from the case of the object lenses 10 and13 of the optical disk, the distance from the case of the optical diskat the optical disk 2 to the end of the magnet 42 in the heightdirection at the optical disk 2 is larger than the distance from thecase of the optical disk to the end of the magnet 39 in the heightdirection at the optical disk 2.

The distances between the optical disk 2 and the magnets 40 and 41,which are tracking magnets for driving the lens holder 16 in the widthdirection, are substantially equal to d39, and the ends of the magnets40 and 41 in the height direction at the optical disk 2 and the end ofthe magnet 39 at the optical disk 2 are positioned at the same distancefrom the optical disk 2. Further, the lengths of the magnets 40 and 41in the height direction, that is, the lengths of the long sides of themagnets 40 and 41 are equal to the length of the magnet 39, which isrepresented by 139. The distances from the optical disk 2 to the lowerends of the magnets 40 and 41, respectively, are substantially equal tothe distance from the optical disk 2 to the lower end of the magnet 39.Further, the distances are substantially equal to d39+139. That is, thedistances from the surface of the optical disk 2, on which informationis recorded, to the ends of the magnets 39 to 42 in the heightdirection, which are opposite to the ends thereof at the optical disk 2,are substantially equal to each other, in a state where the optical disk2 is mounted on the spindle motor 25. In other words, the lower endsurfaces of the magnets 39 to 42, formed by connecting the ends of themagnets 39 to 42 in the height direction which are opposite to the endsthereof at the optical disk 2, is substantially parallel to the surfaceof the optical disk 2 on which the information is recorded.

As shown in FIG. 52B, the magnets 39 and 42 are magnetized and disposedin such a manner as described in FIGS. 6 and 7. Reference numerals 39 nand 42 n represent a neutral zone which occurs in a portion where theorientations of magnetic poles of the magnets 39 and 42 are switched andwhich is not magnetized. The neutral zone 39 n is positioned at half thelength of the magnet 39 in the longitudinal direction, and the lengthfrom the lower end of the magnet 42 to the neutral zone 42 n is set tobe substantially equal to the length from the lower end of the magnet 39to the neutral zone 39 n. That is, the lower end surface of the magnets39 to 42 is substantially parallel to a surface formed by connecting theneutral zones 39 n and 42 n. Further, when the lens holder 16 is notdriven, the center positions of the focus coils 33 and 34 and thesub-tracking coils 37 and 38 in the height direction coincide with theposition of the surface formed by connecting the neutral zones 39 n and42 n in the height direction. In other words, a portion corresponding tothe S-pole of the magnet 39 facing the focus coil 33 and thesub-tracking coil 37, a portion corresponding to the N-pole of themagnet 39 facing the focus coil 33 and the sub-tracking coil 37, and aportion corresponding to the S-pole of the magnet 42 facing the focuscoil 34 and the sub-tracking coil 38 have the same area as each other.However, a portion corresponding to the N-pole of the magnet 42 facingthe focus coil 34 and the sub-tracking coil 38 has a smaller area thanthe above-described portions. Such a construction can suppress thetilting of the lens holder 16, which occurs when the lens holder 16 isdriven.

FIG. 53 is a diagram for schematically explaining the behavior of thelens holder 16 when an electric current flows in the focus coils 33 and34 so as to drive the lens holder 16 up and down in the heightdirection. In FIG. 53, the suspensions 18 a to 18 f are collectivelyshown as the suspension 18. If the suspension 18 is seen from the widthdirection of FIG. 51A, the suspension 18 has such a straight-line shapeas shown in FIG. 51B, when the lens holder 16 is not driven. Further,the suspension 18 is fixed to the lens holder 16 and the suspensionholder 17, respectively, by the coupling portions 1816 and 1817.Practically, when the lens holder 16 is driven, the suspension 18 itselfis curved so that the lens holder 16 moves in the height direction.However, FIG. 53 schematically shows that the suspension 18 has astraight line shape even when the lens holder 16 is driven.

When the lens holder 16 is moved equally up and down in the heightdirection from a non-driving position shown by a solid line of FIG. 53,the suspension 18 is stretched obliquely with respect to the surface ofthe optical disk 2 on which information is recorded. Therefore, a largedifference occurs in displacement in the rotation direction (tangentialdirection) of the optical disk 2 shown in FIG. 53.

When an electric current flows in the focus coils 33 and 34 so as tomove the lens holder 16 in a direction away from the optical disk 2, thedistance between the focus coil 33 and the magnet 39 and the distancebetween the focus coil 34 and the magnet 42 do not change too much.

Therefore, there is no large difference between electromagnetic powergenerated in the side of the focus coil 34 and electromagnetic powergenerated in the side of the focus coil 33.

Meanwhile, when an electric current flows in the focus coils 33 and 34so as to move the lens holder 16 in a direction approaching the opticaldisk 2, the difference between the distance between the focus coil 33and the magnet 39 and the distance between the focus coil 34 and themagnet 42 becomes large. As the lens holder 16 moves in a directionapproaching the optical direction, the distance between the focus coil33 and the magnet 39 becomes large and the electromagnetic powergenerated in the side of the focus coil 33 becomes small. However, themagnet 42 is constructed to be shorter in the height direction than themagnet 39 (that is, the magnet 42 is positioned in a lower level thanthe magnet 39). Therefore, as the lens holder 16 moves in a directionapproaching the optical disk 2, electromagnetic power of the magnet 42flowing through the focus coil 34 is reduced, and electromagnetic powergenerated in the side of the focus coil 34 also becomes small.Accordingly, even when the lens holder 16 is moved in a directionapproaching the optical disk 2, there is no large difference betweenelectromagnetic power generated in the side of the focus coil 34 andelectromagnetic power generated in the side of the focus coil 33.Therefore, it is possible to suppress the inclination of the lens holder16.

Next, the inclined-right mirror 9 of the optical pickup device will bedescribed with reference to FIGS. 54 to 59. Further, members shown inFIGS. 54 to 59 have a slightly different shape from the members shown inFIGS. 1 and 5, but have the same functions. Further, although not shown,the optical pickup device shown in FIGS. 54 to 59 is also provided withthe quarter wavelength member 9 a shown in FIGS. 1 and 5.

The inclined-right mirror 9 can be constructed in such a manner as willbe described below with reference to FIG. 54.

FIGS. 54A and 54B are diagrams illustrating the inclined-right mirror 9when the inclined-right mirror 9 is seen from the Z direction of FIG. 5in a direction of the light flux of laser light which is emitted fromthe short wavelength optical unit 1 or the long wavelength optical unit3 so as to pass through the beam splitter 7 or the collimator lens 8.Reference numeral A shown in FIGS. 54A and 54B represents a light fluxof laser light reaching the inclined-right mirror 9.

The inclined-right mirror 9 shown in FIG. 9 includes a reflecting plate9 d and an actuator 9 e. The reflecting plate 9 d is provided with awavelength selecting film 9 b and a reflecting section 9 c. The actuator9 e moves the reflecting plate 9 d. The wavelength selecting film 9 band the reflecting section 9 c are provided on the surface of thereflecting plate 9 d at the beam splitter 7 and are formed of adielectric multilayer or metal.

The wavelength selecting film 9 b provided in the reflecting plate 9 dhas a function of transmitting most of light with a predeterminedwavelength regardless of the polarization state and reflecting most oflight with other wavelengths regardless of the polarization state. Inthis embodiment, short-wavelength light (light with a wavelength ofabout 405 nm) emitted from the short wavelength optical unit 1 istransmitted, and red light (light with a wavelength of about 660 nm) andinfrared light (light with a wavelength of about 780 nm) emitted fromthe long wavelength optical unit 3 are reflected. That is, thewavelength selecting film 9 b has the same construction and function asthat described in FIG. 1.

The reflecting section 9 c provided in the reflecting plate 9 d has afunction of reflecting most of arriving light regardless of thewavelength or the polarization state. Further, when the wavelengthselecting film 9 b and the reflecting section 9 c are provided in thereflecting plate 9 d, the reflecting section 9 c may reflect light witha predetermined wavelength regardless of the polarization state. In thisembodiment, the reflecting section 9 c may reflect at leastshort-wavelength light (light with a wavelength of about 405 nm) emittedfrom the short-wavelength optical unit 1.

The actuator 9 e is provided with a gear 9 f and a motor (not shown)which rotates the gear 9 f. As a motor, a small-sized direct-currentmotor is used. Meanwhile, a rack gear 9 g is provided in one side of thereflecting plate 9 d so as to mesh with the gear 9 f. The reflectingplate 9 d and a case 9 h are constructed so as to freely slide.

In the optical pickup device provided with the reflecting plate 9 dconstructed in such a manner, when the optical disk 2 is mounted on thespindle motor 25 shown in FIGS. 2 to 4, a control member (not shown)discriminates the type of the optical disk 2 and applies a controlsignal to the actuator 9 e. In accordance with the control signal, theactuator 9 e drives the motor so as to rotate the gear 9 f such that thereflecting plate 9 d can be inserted into the case 9 h of the actuator 9e. Here, the actuator 9 e has been described as a member which moves thereflecting plate 9 d by using a motor. However, if the actuator 9 e issuch an actuator that is driven in accordance with a control signal, asolenoid, a linear motor, a hydraulic piston and the like may be used soas to move the reflecting plate 9 d.

FIG. 54A is a diagram showing a state where the reflecting plate 9 d ismoved by the actuator 9 e such that the wavelength selecting film 9 b ispresent on a light path, and FIG. 54B is a diagram showing a state wherethe reflecting plate 9 d is moved by the actuator 9 e such that thereflecting section 9 c is present on the light path.

Hereinafter, the movement of the reflecting plate 9 d depending on thetype of the optical disk 2 to be mounted on the spindle motor 25 will bedescribed.

When the optical disk 2 mounted on the spindle motor 25 is an opticaldisk in which a distance between the surface of the optical disk 2 andthe recording layer is 0.1 mm and recording/reproducing of informationis performed by short-wavelength light (light with a wavelength of about405 nm), the inclined-right mirror 9 is set in such a state that thewavelength selecting film 9 b of the reflecting plate 9 d is positionedon the light path by the driving of the actuator 9 e.

Further, even when the optical disk 2 mounted on the spindle motor 25 isan optical disk in which a distance between the surface of the opticaldisk 2 and the recording layer is 0.6 mm and the recording/reproducingof information is performed by red light (light with a wavelength ofabout 660 nm), the inclined-right mirror 9 is set in such a state thatthe wavelength selecting film 9 b of the reflecting plate 9 d ispositioned on the light path by the driving of the actuator 9 e.

Further, even when the optical disk 2 mounted on the spindle motor 25 isan optical disk in which a distance between the surface of the opticaldisk 2 and the recording layer is 1.2 mm and the recording/reproducingof information is performed by infrared light (light with a wavelengthof about 780 nm), the inclined-right mirror 9 is set in such a statethat the wavelength selecting film 9 b of the reflecting plate 9 d ispositioned on the light path by the driving of the actuator 9 e.

Meanwhile, when the optical disk 2 mounted on the spindle motor 25 is anoptical disk in which a distance between the surface of the optical disk2 and the recording layer is 0.6 mm and the recording/reproducing ofinformation is performed by short-wavelength light (light with awavelength of about 405 nm), the inclined-right mirror 9 is set in sucha state that the reflecting section 9 c of the reflecting plate 9 d ispositioned on the light path by the driving of the actuator 9 e.Further, even when the optical disk 2 mounted on the spindle motor 25 isan optical disk, in which a distance between the surface of the opticaldisk 2 and the recording layer is 0.6 mm and the recording/reproducingof information is performed by red light (light with a wavelength ofabout 660 nm), or an optical disk in which a distance between thesurface of the optical disk 2 and the recording layer is 1.2 mm and therecording/reproducing of information is performed by infrared light(light with a wavelength of about 780 nm), the inclined-right mirror 9may be set in such a state that the reflecting section 9 c of thereflecting plate 9 d is positioned on the light path by the driving ofthe actuator 9 e.

FIGS. 55A and 55B are schematic views illustrating a light path of laserlight in the optical pickup device using the inclined-right mirror 9 ofFIG. 54. FIG. 55A shows a state where the wavelength selecting film 9 bis positioned on the light path, and FIG. 55B shows a state where thereflecting section 9 c is positioned on the light path. In addition tothe construction described by referring to FIG. 1, the optical part 11provided between the inclined-right mirror 9 and the object lens 10includes an aperture filter and an auxiliary hologram. The aperturefilter provides a number of apertures which are required for the opticaldisk 2 in which a distance between the surface of the optical disk 2 andthe recording layer is 0.6 mm and the recording/reproducing ofinformation is performed by short-wavelength light (light with awavelength of about 405 nm). The auxiliary hologram having wavelengthselection properties reacting with short-wavelength light (light with awavelength of 405 nm) performs spherical aberration correction or colorcorrection. The aperture filter and the auxiliary hologram may beconstructed integrally with the optical part 11 or may be constructedseparately from the optical part 11.

Hereinafter, the light path of the optical pickup device depending on adifference in type of the optical disk 2 mounted on the spindle motor 25will be described.

When the optical disk 2 mounted on the spindle motor 25 is an opticaldisk in which a distance between the surface of the optical disk 2 andthe recording layer is 0.1 mm and recording/reproducing of informationis performed by short-wavelength light (light with a wavelength of about405 nm), the inclined-right mirror 9 is set in such a state that thewavelength selecting film 9 b of the reflecting plate 9 d is positionedon the light path, as shown in FIG. 55A. The short-wavelength light(light with a wavelength of about 405 nm), which has been emitted fromthe short wavelength optical unit 1 so as to pass through the beamsplitter 7 or the collimator lens 8, is transmitted through thewavelength selecting film 9 b of the inclined-right mirror 9 so as to bereflected by the inclined-right mirror 12. Then, the short-wavelengthlight passes through the object lens 13 so as to be condensed on arecording layer which is positioned where a distance from the surface ofthe optical disk 2 is 0.1 mm.

Further, even when the optical disk 2 mounted on the spindle motor 25 isan optical disk in which a distance between the surface of the opticaldisk 2 and the recording layer is 0.6 mm and the recording/reproducingof information is performed by red light (light with a wavelength ofabout 660 nm), the inclined-right mirror 9 is set in such a state thatthe wavelength selecting film 9 b of the reflecting plate 9 d ispositioned on the light path, as shown in FIG. 55A. The red light (lightwith a wavelength of about 660 nm), which has been emitted from the longwavelength optical unit 3 so as to pass through the beam splitter 7 orthe collimator lens 8, is reflected by the wavelength selecting film 9 bof the inclined-right mirror 9. Then, the red light passes through theoptical part 11 and the object lens 10 so as to be condensed in arecording layer which is positioned where a distance from the surface ofthe optical disk 2 is 0.6 mm.

Further, even when the optical disk 2 mounted on the spindle motor 25 isan optical disk in which a distance between the surface of the opticaldisk 2 and the recording layer is 1.2 mm and the recording/reproducingof information is performed by infrared light (light with a wavelengthof about 780 nm), the inclined-right mirror 9 is set in such a statethat the wavelength selecting film 9 b of the reflecting plate 9 d ispositioned on the light path, as shown in FIG. 55A. The infrared light(light with a wavelength of about 780 nm), which has been emitted fromthe long wavelength optical unit 3 so as to pass through the beamsplitter 7 or the collimator lens 8, is reflected by the wavelengthselecting film 9 b of the inclined-right mirror 9. Then, the infraredlight passes through the optical part 11 and the object lens 10 so as tobe condensed in a recording layer which is positioned where a distancefrom the surface of the optical disk 2 is 1.2 mm.

Meanwhile, when the optical disk 2 mounted on the spindle motor 25 is anoptical disk in which a distance between the surface of the optical disk2 and the recording layer is 0.6 mm and the recording/reproducing ofinformation is performed by short-wavelength light (light with awavelength of about 405 nm), the inclined-right mirror 9 is set in sucha state that the reflecting section 9 c of the reflecting plate 9 d ispositioned on the light path, as shown in FIG. 55B. The short-wavelengthlight (light with a wavelength of about 405 nm), which has been emittedfrom the short wavelength optical unit 1 so as to pass through the beamsplitter 8 or the collimator lens 8, is reflected by the wavelengthselecting film 9 b of the inclined-right mirror 9. Then, theshort-wavelength light passes through the object lens 10 so as to becondensed in the recording layer which is positioned where a distancefrom the surface of the optical disk 2 is 0.6 mm.

The reflecting plate 9 d of the inclined-right mirror 9, described inthe FIG. 54, can be constructed in such a manner as will be describedwith reference to FIG. 56. Further, portions which are not described arethe same as those described by referring to FIGS. 54 and 55.

In the portion of the wavelength selecting film 9 b shown in FIG. 54, abase material portion 9 i in which a base material of the reflectingplate 9 d is exposed is set without the wavelength selecting film 9 b.The surface of the reflecting plate 9 d at the beam splitter 7 iscomposed of a portion (base material portion 9 i), which is not providedwith the reflecting section 9 c, and a portion provided with thereflecting section 9 c described by referring to FIG. 54.

The base material portion 9 i provided on the reflecting plate 9 d has afunction of transmitting most of arriving light regardless of thewavelength or the polarization state. When the base material portion 9 iand the reflecting section 9 c are provided on the reflecting plate 9 d,the base material 9 i may transmit light with a predetermined wavelengthregardless of the polarization state. Here, the base material portion 9i may be constructed so as to reflect at least short-wavelength light(light with a wavelength of 405 nm) emitted from the short wavelengthoptical unit 1.

The reflecting section 9 c provided on the reflecting plate 9 d has afunction of reflecting most of arriving light regardless of thewavelength or the polarization state. Here, the reflecting section 9 cis constructed so as to reflect at least short-wavelength light (lightwith a wavelength of about 405 nm), emitted from the short wavelengthoptical unit 1, and red light (light with a wavelength of about 660 nm)and infrared light (light with a wavelength of about 780 nm), emittedfrom the long wavelength optical unit 3.

Hereinafter, the movement of the reflecting plate 9 d, provided with thebase material portion 9 i and the reflecting section 9 c, depending onthe optical disk 2 mounted on the spindle motor 25 will be described.

When the optical disk 2 mounted on the spindle motor 25 is an opticaldisk in which a distance between the surface of the optical disk 2 andthe recording layer is 0.1 mm and recording/reproducing of informationis performed by short-wavelength light (light with a wavelength of about405 nm), the inclined-right mirror 9 is set in such a state that thebase material portion 9 i of the reflecting plate 9 d is positioned onthe light path by the driving of the actuator 9 e.

Further, even when the optical disk 2 mounted on the spindle motor 25 isan optical disk in which a distance between the surface of the opticaldisk 2 and the recording layer is 0.6 mm and the recording/reproducingof information is performed by red light (light with a wavelength ofabout 660 nm), the inclined-right mirror 9 is set in such a state thatthe reflecting section 9 c of the reflecting plate 9 d is positioned onthe light path by the driving of the actuator 9 e.

Further, even when the optical disk 2 mounted on the spindle motor 25 isan optical disk in which a distance between the surface of the opticaldisk 2 and the recording layer is 1.2 mm and the recording/reproducingof information is performed by infrared light (light with a wavelengthof about 780 nm), the inclined-right mirror 9 is set in such a statethat the reflecting section 9 c of the reflecting plate 9 d ispositioned on the light path by the driving of the actuator 9 e.

Further, even when the optical disk 2 mounted on the spindle motor 25 isan optical disk in which a distance between the surface of the opticaldisk 2 and the recording layer is 0.6 mm and recording/reproducing ofinformation is performed by short-wavelength light (light with awavelength of about 405 nm), the inclined-right mirror 9 is set in sucha state that the reflecting section 9 c of the reflecting plate 9 d ispositioned on the light path by the driving of the actuator 9 e.

FIGS. 56A and 56B are schematic views illustrating the light path oflaser light in the optical pickup device using the inclined-right mirror9 provided with the base material portion 9 i and the reflecting section9 c. FIG. 56A shows a state where the base material 9 i is positioned onthe light path, and FIG. 56B shows a state where the reflecting section9 c is positioned on the light path.

Even when the reflecting plate 9 d provided with the base materialportion 9 i and the reflecting section 9 c is used, the light path oflaser light shown in FIGS. 56A and 56B is the same as that when thereflecting plate 9 d described by referring to FIGS. 54 and 55 is used.

The inclined-right mirror 9 can be constructed in such a manner as willbe described with reference to FIG. 57.

Similar to FIG. 54, FIGS. 57A and 57B are diagrams illustrating theinclined-right mirror 9 when the inclined-right mirror 9 is seen fromthe Z direction of FIG. 5 in a direction of the light flux of laserlight which is emitted from the short wavelength optical unit 1 or thelong wavelength optical unit 3 so as to pass through the beam splitter 7or the collimator lens 8. Reference numeral A shown in FIGS. 57A and 57Brepresents a light flux of laser light reaching the inclined-rightmirror 9.

In FIG. 57, the inclined-right mirror 9 includes an electric controlfilm 9 j and a signal applying section 9 k, which are provided on thesurface thereof at the beam splitter 7. The electric control film 9 j isa switching unit of which the optical characteristics changes inaccordance with a control signal, and the signal applying section 9 kapplies a control signal to the electric control film 9 j.

The electric control film 9 j has a state of the wavelength selectingfilm 9 b and a state of the reflecting section 9 c, which have beendescribed with reference to FIG. 54. In accordance with a controlsignal, two of the states are switched. The states of the electriccontrol film 9 j are switched depending on the type of the optical disk2 mounted on the spindle motor 25 so as to correspond to the movement ofthe reflecting plate 9 d described in FIGS. 54 and 55. Then, as shown inFIGS. 58A and 58B, the light path of laser light can be switched thesame as in FIGS. 55A and 55B.

Moreover, the electric control film 9 j is constructed to have a stateof the base material 9 i and a state of the reflecting section 9 c,which have been described with reference to FIG. 54. In accordance witha control signal, two of the states are switched. The states of theelectric control film 9 j are switched depending on the type of theoptical disk 2 mounted on the spindle motor 25 so as to correspond tothe movement of the reflecting plate 9 d described in FIGS. 54 and 56.Then, as shown in FIGS. 59A and 59B, the light path of laser light canbe switched the same in FIGS. 56A and 56B.

According to the optical pickup device described with reference to FIGS.54 to 59, the light path of laser light can be switched depending on thetype of the optical disk 2. Therefore, recording/reproducing can beperformed on great variety of optical disks 2 of which the distances tothe recording layer or the wavelengths to be used are different fromeach other. Particularly, since short-wavelength light (with awavelength of about 405 nm) is used, recording/reproducing ofinformation can be also performed on both of the optical disks 2 inwhich the distances between the surface and the recording layer aredifferent from each other (0.1 mm and 0.6 mm).

As the construction around the lens holder 16 described with referenceto FIGS. 6 to 8, such a construction as will be described with referenceto FIGS. 60 to 74 can be also applied. Further, members which are notdescribed are the same as those described so far. Therefore, the samereference numerals will be attached thereto, and the descriptionsthereof will be omitted.

FIG. 60 is a diagram illustrating the optical pickup device according tothis embodiment. In the optical pickup device 301 shown in FIG. 60,reference numeral 302 represents a cover which is composed of an uppercover 302 a and a lower cover 302 b. The cover 302 is formed in a bagshape, having an opening 302 c formed on one end thereof. A tray 303 isheld by the cover 303 so as to be inserted into and drawn out of thecover 303 in the X direction shown in FIG. 60. The tray 303 is formed ofa light material such as resin or the like. The tray 303 has a bezel 304provided on the front portion thereof. The bezel 304 serves to block theopening 302 c when the tray 303 is housed into the cover 302. The bezel304 has an eject button 305 exposed thereon. With the eject button 305being pressed, the tray 303 is slightly popped out of the cover 302 by amechanism (not shown) in the X direction shown in FIG. 303. Then, thetray 303 can be put into or drawn out of the cover 302 in the Xdirection.

The tray 303 has a pickup module 306 attached thereto. The pickup module306 has the spindle motor 25 provided thereto, the spindle motor 25rotationally driving the optical disk 2. Further, the base 15 is movablyprovided to the pickup module 306 so as to approach or depart from thespindle motor 25. Although not described in detail, the lens holder 16is attached to the base 15 so as to be elastically moved. The lensholder 16 has the object lenses 10 and 13 attached thereto. In the base15, a base cover 15 f is attached on the surface of the base 15 which isopposite to the information recording surface of the optical disk 2 tobe mounted on the spindle motor 25, the base cover 15 f being formed ofa metallic plate. The base cover 15 covers at least portions of theflexible board 29, the lens holder 16 and the like, which are attachedto the base 15. Accordingly, the parts attached to the base 15 can beprevented from coming in contact with the optical disk 2. Reversely,these parts can be protected from dust or electric noise.

Reference numerals 307 and 308 represent rails which are held by thelower cover 302 b and are engaged with both sides of the tray 303. Therails 307 and 308 are constructed so as to slide in a predeterminedrange with respect to the lower cover 302 b and the tray 303 in the Xdirection where the tray 303 is inserted and drawn out.

Next, the base 15 provided to the pickup module 306 will be described indetail.

FIG. 61 is a perspective view illustrating the overall base 15. For thesake of description, FIG. 61 shows a state where such parts as the basecover 15 f, the flexible board 29 and the like are removed from the base15. In FIG. 61, the focus direction indicates a direction of the opticalaxes of the object lenses 10 and 13. The focus direction is parallel tothe rotating shaft of the spindle motor 25. The tracking directionindicates a direction which is parallel to the surface of the suspensionholder 17, on which the suspension 18 is fixed, and is perpendicular tothe focus direction. The tangential direction indicates a directionwhich is perpendicular to the focus direction and the trackingdirection.

As described with reference to FIGS. 3 and 4, the base 15 is movablyattached to the shafts 21 and 22.

Roughly speaking, the base 15 includes the short wavelength optical unit1 which emits and receives short-wavelength light, the long wavelengthoptical unit 3 which emits and receives long-wavelength light, and thelens holder 16 having the object lenses 10 and 13 mounted thereon.

The lens holder 16 and the suspension holder 17 are elasticallysupported by the suspensions 18. The suspension holder 17 is fixed tothe yoke member 32 by a technique such as bonding, and the yoke member32 is also bonded to the base 15 by a technique such as bonding.

Next, the construction around the lens holder 16 including the yokemember 32 to be attached to the base 15 will be described in detail.

FIGS. 62 to 65 are diagrams showing a state where such parts as the lensholder 16, the suspension holder 17, the suspensions 18, the yoke member32 and the like are detached from the optical pickup device described inFIG. 61. FIG. 62 is a perspective view of the optical pickup device,FIG. 63 is a plan view of the optical pickup device shown in FIG. 62,FIG. 64 is a sectional view of the optical pickup device taken along A-Aline of FIG. 63, and FIG. 65 is a sectional view of the optical pickupdevice taken along B-B line of FIG. 63.

Referring to FIGS. 62 to 65, the yoke member 32 will be described. Theyoke member 32 has upright portions 32 a to 32 j, which are integrallyprovided thereon by a cutting and raising process. Among them, theupright portions 32 a, 32 b, 32 c, 32 g, 32 h, 32 i, and 32 j are formedso as to face the respective coils provided in the lens holder 16, andthe upright portions 32 e and 32 f, respectively, are formed so as toface the suspensions 18 such that the pair of three suspensions 18interpose the lens holder 16.

On the lower surface of the yoke member 32, an opening 32 d is provided,from which the inclined-right mirrors 9 and 12 fixed to the base 15enter.

When the yoke member 32 is attached to the base 15, the yoke member 32becomes parallel to the plane formed in the center axes of the shafts 21and 22 shown in FIG. 61. A portion forming the opening 32 d is referredto as a main surface portion 32 k of the yoke member 32. The uprightportions 32 a to 32 j are provided so as to be substantiallyperpendicular to the main surface portion 32 k.

In the yoke member 32, focus magnets 136 to 139 and tracking magnets 140to 143 are provided by a technique such as bonding.

The magnet 136 is attached on the upright portion 32 c so as to face thefocus coil 130, the magnet 137 is attached on the upright portion 32 cso as to face the focus coil 131, the magnet 138 is attached on theupright portion 32 b so as to face the focus coil 132, and the magnet139 is attached on the upright portion 32 a so as to face the focus coil133. The magnets 136 and 137 are attached on both ends of the upright 32c in the tracking direction shown in FIG. 63 so as to face the focuscoils 130 and 131, respectively. In this embodiment, the upright portion32 c is widely formed in the tracking direction shown in FIG. 63, inorder to increase the rigidity of the yoke member 32. However, theupright portions 32 c may be divided into two portions such that thefocus magnet 136 is attached on one portion by bonding or the like andthe focus magnet 137 is attached on the other portion.

The tracking magnet 140 is attached on the upright portion 32 g so as toface the tracking coil 134, the tracking magnet 141 is attached on theupright portion 32 h so as to face the tracking coil 134, the trackingmagnet 142 is attached on the upright portion 32 i so as to face thetracking coil 135, and the tracking magnet 143 is attached on theupright portion 32 j so as to face the tracking coil 135.

In the focus magnets 136 and 137 and the tracking magnets 140 to 143, atleast portions of the bottom surfaces thereof are supported or fixed tothe main surface portion 32 k. Through such a construction, thepositioning of the magnets is easily performed.

Next, an example of the magnetization of magnet will be shown. The focusmagnets 136 and 138 are magnetized so that the magnetic poles thereofare exposed to the surfaces facing the focus coils 130 and 132,respectively, in an order of the S-pole and the N-pole in the focusdirection of FIG. 64 from the bottom surface toward the objects lenses10 and 13. The focus magnets 137 and 139 are magnetized so that themagnetic poles thereof are exposed to the surfaces facing the focuscoils 131 and 133, respectively, in an order of the N-pole and theS-pole in the focus direction of FIG. 65 from the bottom surface towardthe object lenses 10 and 13. Further, the tracking magnets 140 and 143are magnetized so that the N-pole is exposed to the surfaces facing thetracking coils 134 and 135, respectively, and the tracking magnets 141and 142 are magnetized so that the S-pole is exposed to the surfacesfacing the tracking coils 134 and 135.

The suspensions 18 are formed, disposed, and constructed as describedwith reference to FIG. 6. Through the suspensions 18, an electriccurrent flows in the respective coils provided in the lens holder 16.

An example of wiring lines between the suspensions 18 and the respectivecoils provided in the lens holder 16 will be described.

The focus coils 130 and 132 are connected in series to each other, andboth ends of the coil group are electrically connected to thesuspensions 18 a and 18 b, respectively. Further, the focus coils 131and 133 are connected in series to each other, and both ends of the coilgroup are electrically connected to the suspensions 18 d and 18 e,respectively. Further, the focus coils 134 and 135 are connected inseries to each other, and both ends of the coil group are electricallyconnected to the suspensions 18 c and 18 f, respectively. The ends ofthe respective coils and the suspensions 18 are electrically connectedby a metallic bonding material such as solder or lead-free solder.

As shown by oblique lines in FIG. 63, the optical pickup deviceaccording to this embodiment includes a gel pocket 144 composed of thesuspension holder 17, the upright portion 32 b, the upright portion 32e, and the focus magnet 138 and a gel pocket 145 composed of thesuspension holder 17, the upright portion 32 a, the upright portion 32f, and the focus magnet 139. In the gel pockets 144 and 145 throughwhich portions of the suspensions 18 penetrate, an elastic material suchas damper gel for damping is filled. That is, portions of thesuspensions 18, or more specifically, the roots of the suspensions 18 atthe suspension holder 17 are wrapped by the elastic material.Accordingly, it is possible to suppress unnecessary resonance of thesuspensions 18 when the lens holder 16 is driven in the focus ortracking direction. As for the elastic material, such a material that isgelated by the irradiation of ultraviolet rays can be used.

Next, a portion of the lens holder 16, which holds the lens holder 10and 13, will be described with reference to FIG. 63.

As shown in FIG. 63, the lens holder 16 includes the object lens supportsurfaces 110 d, 110 e, 110 f (collectively referred to as the objectlens support surfaces 110) formed in the substantially same shape, thebonding sections 111 d, 111 e, 111 f, 111 g, 111 h, and 111 i(collectively referred to as the bonding sections 111) formed in thesubstantially same shape, and the bonding sections 113 a, 113 b, and 113c (collectively referred to as the bonding sections 113) formed in thesubstantially same shape.

As shown in FIG. 63, the object lens support surfaces 110 d, 110 e, and110 f are disposed at even intervals around the circumferential edge ofthe object lens 10 (more specifically, the through-hole 16 a). In otherwords, the object lens support surfaces 110 d, 110 e, and 110 f aredisposed at an interval of 120 degrees, seen from the center of theobject lens 10 (more specifically, the through-hole 16 a). Further, thebonding sections 111 d and 111 e are disposed in both ends of the objectlens support surface 110 d, the bonding sections 111 f and 111 g aredisposed in both ends of the object lens support surface 110 e, and thebonding sections 111 h and 111 i are disposed in both ends of the objectlens support surface 110 f. That is, the bonding sections 111 d, 111 f,and 111 h are disposed at even intervals, and the bonding sections 111e, 111 g, and 111 i are also disposed at even intervals. As the objectlens support surfaces 110 are disposed at even intervals around thecenter axis of the object lens 10 (more specifically, the through-hole16 a), the object lens 10 can be stably supported by the object lenssupport surface 110. Further, with the bonding sections being disposedas described above, a force by which the object lens 10 is pulled fromthe lens holder 16 is canceled, even though an adhesive injected intothe bonding sections 111 is contracted when being solidified. Further,the positioned object lens 10 is hardly shifted.

Except for the disposition of the object lens support surfaces 110 andthe bonding sections 111 with respect to the circumferential edge of thethrough-hole 16 a and the setting of angle occupied in thecircumferential edge of the through-hole 16 a by the object lens supportsurfaces 110, the construction of the portion shown in FIG. 63 is almostthe same as that described with reference to FIGS. 31 to 35. Therefore,the descriptions thereof will be omitted.

In the object lenses 10 and 13, the object lens 10 is formed of acombination of glass and resin. Accordingly, since a technique such asmetallic molding can be used, a hologram is easily provided on theobject lens 10, and it is possible to adjust a spherical aberration oflight with various kinds of wavelengths. Except that the object lens 10is formed of a combination of glass and resin, the construction of theobject lens 10 is the same as that described with reference to FIGS. 34and 35. As the object lens 13, an object lens formed of glass is used,similar to that of FIGS. 31 to 35.

FIG. 65 is a sectional view illustrating the optical pickup deviceaccording to this embodiment, taken along A-A line of FIG. 63.

As shown in FIG. 65, the lens holder 16 is provided with thethrough-holes 16 a and 16 b. The object lenses 10 and 13 are broughtdown into the through-holes 16 a and 16 b, respectively, from adirection of an arrow P1 shown in FIG. 65 and are fixed by alight-curing adhesive. At this time, the outer circumferences of theobject lenses 10 and 13 are abutted on the circumferential edges of thethrough-holes 16 a and 16 b of the lens holder 16. Further, the opticalpart 11, the achromatic diffraction lens 14, and the quarter wavelengthplate 19 are inserted into the through-holes 16 a and 16 b from adirection of an arrow P2 of FIG. 65 and are also fixed by a light-curingadhesive or instant adhesive. At this time, the outer circumferences ofthe optical part 11, the achromatic diffraction lens 14, and the quarterwavelength plate 19 are abutted on the circumferential edges of thethrough-holes 16 a and 16 b of the lens holder 16. Further, these partsare disposed in the lens holder 16 in an order of the object lens 10 andthe optical part 11 and in an order of the object lens 13, theachromatic diffraction lens 14, and the quarter wavelength plate 19,when seen from the side of the optical disk 2 in the focus direction.

On the end surface of the lens holder 16 at the focus coils 130 and 131,a mechanical stopper 16 d is provided so as to project from the lensholder 16 toward the upright portion 32 c. On the end surface of thelens holder 16 at the focus coils 132 and 133, a mechanical stopper 16 eis provided so as to project from the lens holder 16 toward thesuspension holder 17. If the lens holder 16 largely moves toward theobject lenses 10 and 13, that is, toward the optical disk 2 in the focusdirection shown in FIG. 65, the upper surfaces of the mechanicalstoppers 16 d and 16 e are abutted on the rear surface of the base cover15 f described in FIG. 60. Then, the movement of the lens holder 16 isregulated so as not to approach the side of the optical disk 2 any more.

Next, the construction around the lens holder 16 to be attached to theyoke member 32 will be described in detail.

FIGS. 66 and 68 are diagrams illustrating the optical pickup device in astate where the yoke member 32 is omitted from the optical pickup devicedescribed in FIGS. 62 to 65. FIG. 66 is a perspective view of theoptical pickup device, FIG. 67 is a plan view of the optical pickupdevice shown in FIG. 66, and FIG. 68 is a bottom view of the opticalpickup device shown in FIG. 66.

As shown in FIG. 67, the lens holder 16 has the object lenses 10 and 13attached thereon.

An object-lens principal point 10 d, which is the principal point of theobject lens 10, substantially coincides with the center of the sphericalsurface of the object lens support surface 110 and is present on thecenter axis of the through-hole 16 a. Although the optical axis of theobject lens 10 substantially coincides with the center axis of thethrough-hole 16 a, the optical axis of the object lens 10 can be shiftedbecause the object lens 10 is tilt-adjusted. Since FIG. 67 is a planview, the object lens principal point 10 d also indicates the centeraxis of the through-hole 16 a and the optical axis of the object lens10.

An object-lens principal point 13 d, which is the principal point of theobject lens 13, is present on the center axis of the through-hole 16 b.The center axis of the through-hole 16 b substantially coincides withthe optical axis of the object lens 13. Since FIG. 67 is a plan view,the object lens principal point 13 d also indicates the center axis ofthe through-hole 16 b and the optical axis of the object lens 13.

A surface, which passes through the object-lens principal points 10 dand 13 d and is perpendicular to the horizontal portion of the lensholder upper surface 16 c or the main surfaces of the mechanicalstoppers 16 d and 16 e, is set to a surface 10 d-13 d. Naturally, thesurface 10 d-13 d coincides with a plane including the center axis ofthe through hole 16 a and the center axis of the through-hole 16 b andsubstantially coincides with a plane including the optical axis of theobject lens 10 and the optical axis of the object lens 13. In otherwords, the surface 10 d-13 d is such a surface that is defined by thetangential direction and the focus direction through the center of thetracking direction of the lens holder 16.

Next, the disposition of the coils will be described.

As shown in FIG. 69, the focus coils 130 to 133 are wound in asubstantial ring shape and in the substantially same shape as eachother. Further, the focus coils 130 to 133 are provided in four cornersof the lens holder 16, respectively. The tracking coils 134 and 135 arewound in a substantial ring shape and the substantially same shape aseach other. Further, one sides of the tracking coils 134 and 135 areinserted into grooves 16 j and 16 k, respectively, provided in thecentral portion of the lens holder in the tangential direction. Thetracking coil 134 is provided between the focus coils 130 and 132, andthe tracking coil 135 is provided between the focus coils 131 and 133.The other sides of the tracking coils 134 and 135, which are notinserted into the grooves 16 j and 16 k, are respectively disposed inthe position interposed between the tracking magnets 140 and 141 and theposition interposed between the tracking magnets 142 and 143. As therespective coils are disposed in such a manner, it is possible tosuppress unnecessary inclination of the lens holder. When the coils arebonded to the lens holder 16, a heat-curing adhesive is preferably used.However, the bonding can be performed by using a light-curing adhesiveor another adhesive. Further, if the respective coils and the lensholder 16 can be reliably disposed in predetermined positions, thebonding may be performed by other methods.

Further, the disposition of the coils will be described in detail.

FIG. 67 is a diagram illustrating the vicinities of the lens holder 16in the optical disk drive, seen from the Z direction shown in FIG. 61.In other words, FIG. 67 is a diagram seen from the side of the opticaldisk 2 in the optical axis direction of the object lenses 10 and 13 or adiagram seen from the side of the optical disk 2 in the focus direction.

The focus coil 130 is provided in the end surface of the lens holder 16which is opposite to the suspension holder 17 and is provided in theside of the lens holder 16 where the suspensions 18 d, 18 e, and 18 fare provided.

The focus coil 131 is provided in the end surface of the lens holder 16which is opposite to the suspension holder 17 and is provided in theside of the lens holder 16 where the suspensions 18 a, 18 b, and 18 care provided.

The focus coil 132 is provided in the end surface of the lens holder 16at the suspension holder 17 and is provided in the side of the lensholder 16 where the suspensions 18 d, 18 e, and 18 f are provided.

The focus coil 133 is provided in the end surface of the lens holder 16at the suspension holder 17 and is provided in the side of the lensholder 16 where the suspensions 18 a, 18 b, and 18 c are provided.

Further, the tracking coils 134 and 135 are respectively provided in theposition interposed between the focus coils 130 and 132 and in theposition interposed between the focus coils 131 and 133.

In the focus coils 130 to 133, reference numerals 130 a, 131 a, 132 a,and 133 a represent the respective centers thereof, reference numerals130 b, 131 b, 132 b, and 133 b represent the respective outercircumferences thereof opposite to the surface 10 d-13 d, referencenumerals 130 c, 131 c, 132 c, and 133 c represent the respective outercircumferences thereof at the surface 10 d-13 d, reference numerals 130d, 131 d, 132 d, and 133 d represent the respective winding coilsurfaces thereof at the suspension holder 17, reference numerals 130 e,131 e, 132 e, and 133 e represent the respective winding coil surfacesthereof opposite to the suspension holder 17, and reference numerals 130f, 131 f, 132 f, and 133 f represent the respective axes thereof. Thefocus coils 130 to 133 are formed by winding in a ring shape. Forexample, when the focus coil 130 is formed, winding is performed in astate where a line, which passes through the center 130 a defined afterthe formation of the focus coil 130 and is perpendicular to thesubstantially ring-shaped plane obtained after the formation of thefocus coil 130, that is, the winding coil surfaces 130 d and 130 e, isset to a virtual center axis for winding coil. Similarly, when the focuscoil 131 is formed, winding is performed in a state where a line passingthrough the center 131 b and perpendicular to the winding coil surfaces131 d and 131 e is set to a virtual center axis for winding coil.Similarly, when the focus coil 132 is formed, winding is performed in astate where a line passing through the center 132 b and perpendicular tothe winding coil surfaces 132 d and 132 e is set to a virtual centeraxis for winding coil. Similarly, when the focus coil 133 is formed,winding is performed in a state where a line passing through the center133 b and perpendicular to the winding coil surfaces 133 d and 133 e isset to a virtual center axis for winding coil. Then, the virtual centeraxes defined when the focus coils 130 to 133 are formed become the axes130 f, 131 f, 132 f, and 133 f shown in FIG. 70, respectively.

In the tracking coils 134 and 135, reference numerals 134 a and 135 arepresent the respective centers thereof, reference numerals 134 b and135 b represent the outer circumferences thereof opposite to the surface10 d-13 d, reference numerals 134 c and 135 c represent the outercircumferences thereof at the surface 10 d-13 d, reference numerals 134d and 135 d represent the winding coil surfaces thereof at thesuspension holder 17, reference numerals 134 e and 135 e represent thewinding coil surfaces thereof opposite to the suspension holder 17, andreference numerals 134 f and 135 f represent the axes thereof. Thetracking coils 134 and 135 are formed by winding in a ring shape. Forexample, when the tracking coil 134 is formed, winding needs to beperformed in a state where a line, which passes through the center 134 adefined after the formation of the tracking coil 134 and isperpendicular to the ring-shape plane defined after the formation of thetracking coil 134, that is, the winding coil surfaces 134 d and 134 e,is set to a virtual center axis for winding coil. Similarly, when thetracking coil 135 is formed, winding is performed in a state where aline passing through the center 135 b and perpendicular to the windingcoil surfaces 135 d and 135 e is set to a virtual center axis. Then, thevirtual center axes for winding coil defined when the tracking coils 134and 135 are formed become the axes 134 f and 135 f shown in FIG. 70,respectively.

The axis 130 f passing through the center 130 a, which is the center forwinding coil, is substantially perpendicular to the winding coilsurfaces 130 d and 130 e, is substantially parallel to the surface 10d-13 d, and is substantially perpendicular to the center axes of thethrough-holes 16 a and 16 b and the optical axes of the object lenses 10and 13. The distance from the outer circumference 130 b to the axis 130f is equal to the distance from the outer circumference 130 c to theaxis 130 f. In other words, the axis 130 f is substantiallyperpendicular to the rotating shaft of the spindle motor 25 and issubstantially parallel to the main surface of the optical disk 2 mountedon the spindle motor 25.

The axes 131 f, 132 f, 133 f, 134 f, and 135 f are in theabove-described relationship with the centers 131 a, 132 a, 133 a, 134a, and 135 a, the outer circumferences 131 b, 132 b, 133 b, 134 b, and135 b, the outer circumferences 131 c, 132 c, 133 c, 134 c, and 135 c,the winding coil surfaces 131 d, 132 d, 133 d, 134 d, and 135 d, and thewinding coil surfaces 131 e, 132 e, 133 e, 134 e, and 135 e. Further,the axes 131 f, 132 f, 133 f, 134 f, and 135 f are in theabove-described relationship with the main surface of the optical disk 2mounted on the spindle motor 25. That is, the axes 130 f, 131 f, 132 f,133 f, 134 f, and 135 f are substantially parallel to each other.Through such a construction, a projected area of the optical pickupdevice in the focus direction is reduced. Therefore, a proportionoccupied by the moving section of the optical pickup device on the base15 can be reduced, so that a multi-wavelength responsive optical pickupdevice having a large number of parts can be reduced in size. Further,when two object lenses 10 and 13 are attached on the lens holder 16, andif at least one of the object lenses is such an object lens thatcondenses blue light corresponding to a wavelength of 400 to 415 nm, thenumber of parts notably increases, which makes it difficult to reducethe size of the optical pickup device. However, when the axes 130 f to133 f of the focus coils 130 to 133 and the axes 134 f and 135 f of thetracking coils 134 and 135 are set to be substantially perpendicular tothe optical axes of the object lenses 10 and 13, it is possible tosuppress the optical pickup device from increasing in size due to anincrease in the number of parts. In addition, when the axes 130 f to 133f of the focus coils 130 to 133 are set to be substantially parallel tothe axes 134 f and 135 f of the tracking coils 134 and 135, the opticalpickup device can be suppressed at the minimum from increasing in sizedue to an increase in the number of parts. In this embodiment, the shortwavelength optical unit 1 emits blue laser light with a wavelength of400 to 415 m, and the object lens 13 condenses the blue laser light.

Lines connecting the centers 130 a, 131 a, 132 a, and 133 a,respectively, set to a line 130 a-131, a line 132 a-133 a, a line 130a-132 a, a line 131 a-133 a, a line 130 a-133 a, and a line 131 a-132 a,and a line connecting the centers 134 a and 135 a is set to a line 134a-135 a. If such virtual lines are defined, the object lenses 10 and 13are positioned within a region which is formed by the lines 130 a-131 a,132 a-133 a, 130 a-132 a, and 131 a-133 a, as can be seen from FIG. 67.As such, the plurality of focus coils are disposed so as to surround theregion, in which the object lenses 10 and 13 are attached, in arectangular shape, and the tracking coils 134 and 135 are disposedbetween the center 10 d of the object lens and the center 13 d of theobject lens in the tangential direction. Then, the heat generated fromthe focus coils 130 to 133 and the tracking coils 134 and 135 istransmitted so that a difference in temperature can be prevented fromoccurring depending on a place when the object lenses 10 and 13 arenonuniformly heated. Therefore, the heat generated from the focus coils130 to 133 and the tracking coils 134 and 135 can be prevented fromhaving an effect on the optical characteristics of the object lenses 10and 13.

As shown in FIG. 70, the line 130 a-132 a coincides with the axes 130 fand 132 f, and the line 131 a-133 a coincides with the axes 131 f and133 f.

As shown in FIG. 67, all the center points of the line 130 a-131 a, theline 132 a-133 a, the line 130 a-133 a, the line 131 a-132 a, and theline 134 a-135 a are present on the surface 10 d-13 d. Particularly, thecenter point of the line 130 a-133 a and the center point of the line131 a-132 a cross each other at one point, through which the centerpoint of the line 134 a-135 a is present on the straight line parallelto the focus direction. The straight line is referred to as the centeraxis 148.

Further, the winding coil surfaces 130 d and 131 d, the winding coilsurfaces 132 e and 133 e, the winding coil surfaces 134 e and 135 e, andthe winding coil surfaces 134 d and 135 d, respectively, are present onthe same plane. Surfaces including the respective sets of the windingcoil surfaces are set to a surface 130 d-131 d, a surface 132 e-133 e, asurface 134 e-135 e, and a surface 134 d-135 d, respectively. Four ofthe surfaces are substantially parallel to each other. A distance fromthe surface 130 d-131 d to the surface 134 e-135 e is equal to adistance from the surface 132 e-133 e to the surface 134 d-135 d, and adistance from the surface 130 d-131 d to the line 134 a-135 a is alsoequal to a distance from the surface 132 e-133 e to the line 134 a-135a. In other words, the distance from the focus coil 130 to the trackingcoil 134, the distance from the focus coil 131 to the tracking coil 135,the distance from the focus coil 132 to the tracking coil 134, and thedistance from the focus coil 133 to the tracking coil 135 are all thesame.

Further, the distance from the focus coil 130 to the focus coil 133 isequal to the distance from the focus coil 131 to the focus coil 132.

The outer circumferential portions 130 b and 132 b, the outercircumferential portions 131 b and 132 b, the outer circumferentialportions 130 c and 132 c, and the outer circumferential portions 131 cand 133 c, respectively, are present on the same plane. Surfacesincluding the respective sets of the outer circumferential portions areset to a surface 130 b-132 b, a surface 131 b-133 b, a surface 130 c-132c, and a surface 131 c-133 c. Four of the surfaces are substantiallyparallel to the surface 10 d-13 d. That is, the focus coils 130 and 131,the focus coils 132 and 133, and the tracking coils 134 and 135,respectively, are plane-symmetrical with reference to the surface 10d-13 d. Further, the focus coils 130 and 132 and the focus coils 131 and133, respectively, are line-symmetrical with reference to an extendingline of the line 134 a-135 a. Further, the focus coils 130 and 133, thefocus coils 131 and 132, and the tracking coils 134 and 135,respectively, are line-symmetrical with reference to the center axis148.

As described above, six of the coils (the focus coils 130 to 133 and thetracking coils 134 and 135) are distributed in the lens holder 16. Thatis, the lens holder 16 has the ring-shaped focus coils 130 to 133 andthe ring-shaped tracking coils 134 and 135, which are providedseparately. The tracking coil 134 is disposed between the focus coils130 and 132, and the tracking coil 135 is disposed between the focuscoils 131 and 133. The axes of the focus coils 130 to 133 and thetracking coils 134 and 135 are set to be substantially parallel to eachother. Accordingly, a driving point by the focus coil, a driving pointby the tracking coil, and the center of the lens holder 16 can be easilybrought in line with each other, and the moving section of the opticalpickup device can be accurately driven.

As shown in FIG. 67, mass balancers 146 and 147 are provided on the lensholder 16 by a technique such as bonding. Then, the driving point of thecoil and the center of the lens holder 16 can be more easily brought inline with each other.

If an electric current flows in the coils, heat is generated. However,as the coils in the lens holder 16 are disposed in the above-describedmanner, a large bias hardly occurs in the temperature distribution onthe lens holder 16. Although the object lenses 10 and 13 are heated,severe deformation does not occur.

FIG. 68 is a diagram illustrating the vicinities of the lens holder 16shown in FIG. 67, seen from the rear side of the optical pickup device.In other words, FIG. 69 is a diagram seen from the side of the lowercover 302 b in the optical direction of the object lenses 10 and 13,that is, a diagram seen from the side of the lower cover 302 b in thefocus direction.

As shown in FIG. 68, the through-hole 16 a of the lens holder 16 isblocked by the optical part 11, and the through-hole 16 b is blocked bythe achromatic diffraction lens 14. Further, a portion including thecenter of the achromatic diffraction lens 14 is covered by the quarterwavelength plate 19.

FIG. 69 is a diagram illustrating the moving section of the opticalpickup device described in FIG. 62 to 65.

As shown in FIG. 69, the lens holder 16 has a depression 161 formed inboth sides of the grooves 16 j and 16 k. The above-described adhesive isinjected into the depression 161 so as to fix the tracking coils 134 and135 to the lens holder 16, the tracking coils 134 and 135 being insertedinto the grooves 16 j ad 16 k.

As the main construction considered as the moving section of the opticalpickup device according to this embodiment, there are included theobject lenses 10 and 13, the optical part 11, the achromatic diffractionlens 14, the lens holder 16, the quarter wavelength plate 19, portions(excluding stretching portions) of the suspensions 18 a to 18 f shown inFIG. 69, the focus coils 130 to 133, the tracking coils 134 and 135, andthe mass balancer 146 and 147. In addition to those, solder forconnecting the suspensions 18 and the coils or an adhesive for fixingthe respective parts to the lens holder 16 can be included. In theoptical pickup device according to this embodiment, the center of themoving section and the driving points of the coils are brought in linewith each other. Therefore, it is possible to accurately drive themoving section of the optical pickup device.

FIG. 70 is a diagram showing a state where the lens holder 16, thesuspensions 18, and the mass balancer 146 and 147 are omitted from themoving section of the optical pickup device shown in FIG. 69. FIG. 71 isa diagram seen from a direction of A-A line of FIG. 70. FIG. 72 showsonly the coils and the magnets in the optical pickup device described inFIGS. 62 to 65, with the other members being omitted. FIG. 73 is adiagram seen from a direction of A-A line of FIG. 72, and FIG. 74 is adiagram seen from a direction of B-B line of FIG. 72.

As shown in FIGS. 70 and 71, the optical pickup device of thisembodiment has five of the optical parts (the object lenses 10 and 13,the optical part 11, the achromatic diffraction lens 14, and the quarterwavelength plate 19) mounted thereon.

As shown in FIGS. 72 and 73, the focus magnets 136 to 139, respectively,are multipole-magnetized in the optical pickup device of thisembodiment. Therefore, the focus coils 130 to 133 facing the focusmagnets 136 to 139, respectively, receive electromagnetic power at upperand lower two sides thereof so as to be effectively driven in the focusdirection. Accordingly, the number of turns of each coil can belessened, and the focus coils itself can be reduced in weight such thatthe moving section of the optical pickup device can be reduced inweight.

In the optical pickup device of this embodiment, the number of turns ofthe tracking coils 134 and 135 is larger than that of the focus coils,and the weight per one tracking coil is two times larger than the weightper one focus coil. However, the tracking coils 134 and 135 are providedin the central portion of the lens holder 16 and the light focus coils130 to 133 are provided in the outer edges of the lens holder 16.Therefore, high-order resonance frequency (second-order resonancefrequency) of the lens holder 16 increases.

As the respective magnets dedicated to the focus coils 130 to 133 andthe tracking coils 134 and 135 are provided, the moving section of theoptical pickup device can be driven by a high thrust force.

The optical pickup device and the optical disk drive according to thepresent invention have an effect of realizing the miniaturization andcan be applied to portable electronic apparatuses such as notebookcomputers or electronic apparatuses such as stationary personalcomputers.

Next, the configuration in which the light receiving section 1 c of FIG.1 or 9 is disposed in the vicinity of the moving section of the opticalpickup device will be described with reference to FIG. 75. The lightreceiving section 1 c checks an amount of light emitted from the lightsource section 1 a. Portions which will not be described below areconfigured in the same manner as those which have been described above.Therefore, like numerals will be attached to the same components, andthe descriptions thereof will be omitted.

FIG. 75 is a sectional view taken along A-A line of FIG. 61, showing themember provided in the base 15 in the sectional view taken along B-Bline of the optical pickup device shown in FIG. 63, and a light flux 153emitted from the light source section 1 a.

In FIG. 75, reference numeral 12 represents an inclined mirror attachedto the base 15 by using a light-curing adhesive or the like. In theinclined mirror 12, reference numeral 12 a represents a reflectingsurface which is a plane surface facing an inclined mirror 9 andprovided so as to be substantially parallel to the main surface of theinclined mirror 9, reference numeral 12 b represents a transmittingsurface which is a plane surface provided on the rear surface of thereflecting surface 12 a of the inclined mirror 12, reference numeral 12c represents a surface between the reflecting surface 12 a and thetransmitting surface 12 b which is an upper surface facing the lensholder 16 or the like, and reference numeral 12 d represents a surfacebetween the reflecting surface 12 a and the transmitting surface 12 bwhich is a lower surface facing the upper surface 12 c.

Reference numeral 15 g is a bottom surface of the base 15 which is thefarthest from the object lenses 10 and 13 in the focus direction. Thebottom surface 15 g is configured to be parallel to a plane surfaceconfigured by the tangential direction and the tracking direction.

The angle formed between the reflecting surface 12 a and thetransmitting surface 12 b is about 9°, the angle θ_(12a) formed betweenthe bottom surface 15 g and the reflecting surface 12 a is about 43°,and the angle θ_(12b) formed between the bottom surface 15 g and thetransmitting surface 12 b is about 34°.

The inclined mirror 12 is basically formed of a glass material such asBK7. Optical films are provided on both the main surfaces thereof.

On the reflecting surface 12 a which is one main surface of the inclinedmirror 12, there is provided a dielectric multilayer formed of SiO₂,Al₂O₃, TiO₂ and the like. On the transmitting surface 12 b which is theother main surface, there is provided a reflection preventing layerformed of MgF₂ and the like.

Reference numeral 16 m represents an aperture limiting section whichnarrows an inner diameter of the through-hole 16 b of the lens holder16. The aperture limiting section 16 m is disposed between the objectlens 13 and the achromatic diffraction lens 14 in the focus direction soas to limit the numeric aperture of short-wavelength light to 0.85.

Reference numeral 17 a represents a concave portion of the suspensionholder 17 which is concaved toward the suspension holder 17 from thelens holder 16 in the tangential direction, and reference numeral 32 mrepresents a concave portion of the yoke member 32 which is providedbetween the upright portions 32 a and 32 b and is concaved toward thelens holder 16 from the suspension holder 17 in the tangentialdirection. As shown in FIGS. 62 and 63, the concave portions 17 a and 32m are positioned on a line connecting the centers of the object lenses10 and 13.

Reference numeral 149 represents a condensing lens which is disposedbetween the lens holder 16 and the suspension holder 17 or between theinclined mirror 12 and the suspension holder 17 in the tangentialdirection and is attached to the base 15 by using a light-curingadhesive or the like. The condensing lens 149 is formed of an organicoptical material having a refractive index of 1.5 and is manufactured bydie molding. As shown in FIG. 75, the condensing lens 149 is roughlycomposed of three surfaces.

Reference numeral 149 a represents a lens-shaped condensing surfacewhich is provided on the first surface of the condensing lens 149 andprotrudes toward the inclined mirror 12. The condensing surface 149 a isprovided with a reflection preventing layer and the like. Referencenumeral 149 b is an aperture limiting surface which is provided on thefirst surface of the condensing lens 149 together with the condensingsurface 149 a and is provided around the condensing lens 149 a. Theangle θ_(149b) formed between the bottom surface 15 g and the aperturelimiting surface 149 b is about 82°. The boundary between the condensingsurface 149 a and the aperture limiting surface 149 b is formed in anelliptical shape having the tracking direction as the major axis.

Reference numeral 149 c represents a reflecting surface which is a planesurface provided on the second surface of the condensing lens 149. Theangle θ_(149c) formed between the bottom surface 15 g and the reflectingsurface 149 c is about 49°.

Reference numeral 149 d represents a transmitting surface which is aplane surface provided on the third surface of the condensing lens 149.The transmitting surface 149 d is provided with a reflection preventinglayer. The angle θ_(149d) formed between the bottom surface 15 g and thetransmitting surface 149 d is about 0°. In other words, the transmittingsurface 149 d is substantially parallel to the plane surface configuredby the tangential direction and the tracking direction.

Reference numeral 152 is a support member which is formed of a metallicplate or the like and is screwed to the base 15, as shown in FIG. 61.Reference numeral 152 a is a through-hole which is provided in thesupport member 152 by a pressing process. The main surface of thesupport member 152 fixed to the base 15 is substantially parallel to theplane surface configured by the tangential direction and the trackingdirection.

Reference numeral 151 represents a flexible board attached to thesupport member 152 by using a heat-curing adhesive or the like, andreference numeral 151 a represents a through-hole provided in theflexible board 151 by using a pressing process or the like.

Reference numeral 150 represents a light receiving section which is abare chip IC attached on the flexible board 151, and reference numeral150 a represents a light receiving surface on which a light receivingelement of the light receiving section 150 is provided. In thisembodiment, the object lenses 10 and 13 are disposed on substantiallythe same line, and the light receiving section 150 is provided along thesame line.

The light receiving section 150 is attached on the flexible board 151 bysuch a method as bonding or flip-chip mounting, and the light receivingsurface 150 a is formed so as to face the transmitting surface 149 dwith a region surrounded by the concave portions 17 a and 32 m, thethrough-hole 151 a, and the through-hole 152 a interposed therebetween.

In such a configuration, the light receiving section 150 can check anamount of light emitted from the light resource section 1 a.

In FIG. 61, the flexible board 151 is not shown in order to show othermembers.

As the receiving section 150 is disposed as described with reference toFIG. 75, the receiving section 1 c shown in FIG. 1 or 9 is not needed.Further, the optical section 46 shown in FIG. 1 or 9 does not need to beprovided with the inclined surface 46 a. Therefore, the optical section46 can be formed in a simple shape of which the cross-section isrectangular.

Next, the progress of light will be described.

Reference numeral 153 represents a light flux of short-wavelength lightemitted from the light source section 1 a, and reference numeral 154represents a light axis of the light flux 153.

The light flux 153 passes through the collimator lens 8 (not shown inFIG. 75) so as to reach the inclined mirror 9. The inclined mirror 9 hasthe wavelength selecting film 9 b formed on the surface on which lightemitted from the respective units 1 and 3 is incident, and most of thelight flux 153 which is short-wavelength light passes through theinclined mirror 9.

The light flux 153 passing through the inclined mirror 9 reaches theinclined mirror 12. The reflecting surface 12 a is provided with adielectric multilayer such that about 90% of the light flux (p-wave) 153is reflected and about 10% thereof is transmitted. Accordingly, it ispossible to disperse short-wavelength light.

The light flux 153 reflected by the reflecting surface 12 a passesthrough the quarter wavelength plate 19, the achromatic diffraction lens14, and the object lens 13 so as to reach the optical disk 2 (not shownin FIG. 75). In the light flux (s-wave) 153 which is reflected by theoptical disk 2 so as to reach the inclined mirror 12 by passing throughagain the object lens 13, the achromatic diffraction lens 14, and thequarter wavelength plate 19, 99% of the light flux 153 is reflected bythe reflecting surface 12 a provided with a dielectric multilayer. Thereflected light flux once again passes through the collimator lens 8 andthe like so as to reach the light receiving section 1 b which convertslight into electrical signals and produces RF signals, tracking errorsignals, and focus error signals from the electrical signals.

Meanwhile, the light flux 153 passing through the reflecting surface 12a is refracted. The refracted light flux 153 proceeds in a direction(toward the bottom surface 15 g) away from the object lenses 10 and 13in the focus direction to reach the transmitting surface 12 b. The lightflux 153 passes through the transmitting surface 12 b provided with areflection preventing layer.

The reflecting surface 12 a and the transmitting surface 12 b are notparallel to each other, and the relationship of θ_(12a)>θ_(12b) isestablished.

Accordingly, the direction of the light flux 153 changes before thelight flux 153 is incident on the reflecting surface 12 a and after thelight flux 153 passes through the transmitting surface 12 b. Before thelight flux is incident on the reflecting surface 12 a, the direction ofthe light flux 153 directed toward the bottom surface 15 g changes sothat the angle formed with the bottom surface 15 g is reduced.Alternately, the light flux 153 proceeds in a direction away from thebottom surface 15 g in the focus direction, as shown in FIG. 75. Here,the angle θ₁₅₄ formed between the bottom surface 15 g and the opticalaxis 154 passing through the transmitting surface 12 b is about 8°.Accordingly, the condensing lens 149 on which the light flux 153 passingthrough the transmitting surface 12 b is incident can be disposed withina region of the base 15 in the focus direction.

The cross-sectional shape of the light flux 153, which is perpendicularto the optical axis 154, is substantially circular before the light flux153 is incident on the reflecting surface 12 a. However, after passingthrough the reflecting surface 12 b, the light flux 153 forms asubstantially elliptical cross-sectional shape in which the trackingdirection is set to the major axis. Therefore, it is possible to reducea region within the base 15, which is required for transmitting thelight flux 153. Accordingly, it is possible to configure a slim opticalpickup device.

Since the reflecting surface 12 a and the transmitting surface 12 b arenot parallel to each other, even when light is reflected by thereflecting surface 12 b provided with a reflection preventing layer andis reflected within the inclined mirror 12, the light is transmittedfrom the transmitting surface 12 b at a different angle from the opticalaxis 154 or comes out of the upper surface 12 c without being directedto the condensing lens 149. Accordingly, the light reflected within theinclined mirror 12 is interfered so that an amount of light passingthrough the transmitting surface 12 b can be suppressed from changing.

The light flux 153 passing through the inclined mirror 12 reaches thefirst surface of the condensing lens 149, on which the condensingsurface 149 a and the aperture limiting surface 149 b are provided. Atthis time, the light flux 153 reaches as parallel light.

The light flux 153 reaching the condensing surface 149 a is condensed.The condensed light flux 153 serves as an amount of light required forchecking an amount of light of the light source section 1 a in the lightreceiving section 150. In a state where the third surface provided withthe transmitting surface 149 d is set to a concave surface and the firstsurface is set to a flat surface, the light flux 153 can be condensed.In this case, however, the light flux 153 is parallel light until itreaches the third surface. Therefore, the condensing lens 149 needs tobe enlarged. As the condensing surface 149 a is provided on the firstsurface of the inclined mirror 12, the condensing lens 149 can bereduced in size.

The light flux 13 reaching the aperture limiting surface 149 b issubstantially vertically incident on the aperture limiting surface 149b. Since the light incident from the aperture limiting surface 149 bproceeds into the condensing lens 149 as substantially parallel light,the light does not reach the light receiving surface 150 a.

As the aperture limiting surface 149 b is provided around the condensingsurface 149 a of the condensing lens 149, the aperture limitation of thelight flux 153 reaching the light receiving section 150 can be performedthe same as the light flux 153 of which the aperture limitation isperformed in the aperture limiting section 16 m of the lens holder 16.Further, the optical distance from the reflecting surface 12 a to theaperture limiting surface 149 b can be substantially equalized to theoptical distance from the reflecting surface 12 a to the aperturelimiting section 16 m. Therefore, the condition of the light flux 153 inthe light receiving section 150 can be approximated to that of the lightflux 153 in the object lens 13.

The light flux 153 condensed in the condensing surface 149 a reaches thereflecting surface 149 c. The incident angle of the light flux 153 withrespect to the reflecting surface 149 c is obtained by90°−(θ_(149c)−θ₁₅₄). Here, the incident angle is about 49°. Meanwhile,the critical angle of light from the reflecting surface 149 c into theair becomes Acrsin (1/1.5)≈42°, in a state where the refractive index ofthe condensing lens 149 is set to 1.5 and the refractive index of theair is set to 1. Therefore, the light flux 153 condensed by thecondensing surface 149 a is totally reflected by the reflecting surface149 c. That is, the reflecting surface 149 c is a totally reflectingsurface which is configured so that the light flux 153 is incident at anangle larger than the critical angle. Further, the reflecting surface149 c does not need to be provided with a reflecting layer or the like.Although a reflecting layer is not provided on the reflecting surface149 c, the light flux 153 can be reflected so as to be guided into thelight receiving section 150.

When an angle θ_(x) formed between the reflecting surface 149 c and thelight flux 153 passing through the inclined mirror 12 satisfies thefollowing expression (1) where the refractive index of the condensinglens 149 is n and the refractive index of a medium with which thecondensing lens 149 comes in contact is n₀, the light flux 153 istotally reflected by the reflecting surface 149 c.θ_(x)≦90°−Arcsin(n ₀ /n)  (1)

The light flux 153 reflected by the reflecting surface 149 c passesthrough the transmitting surface 149 d. The light flux 153 incident fromthe condensing surface 149 a is convergent light within the condensinglens 149. Therefore, when the light flux 153 is emitted from thetransmitting surface 149 d as a plane surface into the air, it isrefracted so as to be further converged.

As the condensing surface 149 a, the aperture limiting surface 149 b,and the reflecting lens 149 c are integrally provided in the condensinglens 149, a member having three functions can be configured as one part.Therefore, it is possible to reduce the number of parts and to save aspace.

The light flux 153 emitted from the transmitting surface 149 d passesthrough a region surrounded by the concave portions 17 a and 32 m, thethrough-hole 151 a, and the through-hole 152 a.

As described with reference to FIG. 75, the inclined mirror 12 reflectssome of the light flux 153 from the light source section 1 a andtransmits some of the light flux 153. Further, the light flux 153reflected by the inclined mirror 12 is guided to the object lens 13, andthe light flux 153 passing through the inclined mirror 12 is guided tothe condensing lens 149. Therefore, even in a slim optical pickupdevice, it is possible for the light receiving section 150 toeffectively detect the light emitted from the light source section 1 a.

In the optical pickup device and the optical disk drive, thetemperatures of the devices vary due to a recording or reproducingoperation of the optical disk 2 or depending on a condition where thedevices are used. In the laser element provided in the light sourcesection 1 a or 3 a, the wavelength of emitted light varies in accordancewith the temperature. Further, in the optical part within the opticalpickup device, the transmittance varies in accordance with thetemperature. According to the configuration shown in FIG. 75, the lightreceiving section 150 can be disposed in a position which is opticallyand physically close to the object lens 13. Therefore, in the opticalpickup device, an amount of light flux 153 reaching the object lens 13can be detected by the light receiving section 150. Based on the amountof light detected by the light receiving section 150, an amount of lightemitted from the light source section 1 a can be controlled so as to beset to an amount of light flux 153 obtained in the position of theobject lens 13.

In the above descriptions, the condensing surface 149 a, the aperturelimiting surface 149 b, and the reflecting surface 149 c are integrallyprovided in the condensing lens 149. However, the condensing member, theaperture limiting member, and the reflecting member can be configuredseparately, the condensing surface 149 a can be configured of anothercondensing member such as a hologram, a member for diffusing orabsorbing light can be provided in the aperture limiting surface 149 b,or a reflective layer can be provided on the reflecting surface 149 c.Further, a dish-shaped member having a concave reflecting surface can bedisposed obliquely with respect to the bottom surface 15 g such thatthree functions such as condensing, aperture limitation, and reflectioncan be achieved like the condensing lens 149.

In the above descriptions, the light flux 153 passing through theinclined mirror 12 is reflected by the plane member 149 c insubstantially the same direction as the light flux 153 reflected by theinclined mirror 12. However, if there is a space within the base 15, thelight flux 153 does not need to be reflected by the plane member 149 c.As the light flux 153 is reflected by the plane member 149 c, aprojected area which is seen in the focus direction can be reduced.Further, the light receiving section 150 can be easily attached to theoptical pickup device.

In the above descriptions, both the main surfaces of the inclined mirror12 are formed so as not to be parallel to each other. However, if thereis a space within the base 15, the main surfaces can be formed so as tobe parallel to each other.

In the above descriptions, the light receiving section 150 receivesshort-wavelength light. However, the light receiving section 150 mayreceive long-wavelength light emitted from the light source section 3 aof the long-wavelength optical unit 3. In this case, the light receivingsection 3 c of the long-wavelength optical unit 3 is not needed, and aspace can be further saved.

The optical pickup device and the optical disk drive according to thepresent invention have an effect of realizing the miniaturization andcan be applied to portable electronic apparatuses such as notebookcomputers or electronic apparatuses such as stationary personalcomputers.

This application is based upon and claims the benefit of priority ofJapanese Patent Application No 2005-377966 filed on 2005 Dec. 28, thecontents of which are incorporated herein by reference in its entirety.

1. An optical pickup device comprising: a light source that radiateslaser light; a condensing member that condenses the laser light onto arecording medium; an optical member that reflects some of the laserlight radiated from the light source onto the condensing member andtransmits the rest of the radiated laser light; and a light receivingsensor that receives the rest of the laser light transmitted through theoptical member so as to detect an amount of laser light.
 2. An opticalpickup device, comprising: a first light source that radiates firstlaser light; a second light source that radiates second laser light ofwhich the wavelength is smaller than the first laser light; a firstcondensing member that condenses the first laser light onto a recordingmedium for the first laser light; a second condensing member thatcondenses the second laser light onto a recording medium for the secondlaser light; a first optical member that reflects the first laser lightradiated from the first light source onto the first condensing member; asecond optical member that reflects some of the second laser lightradiated from the second light source onto the second condensing memberand transmits the rest of the radiated second laser light; and a lightreceiving sensor that receives the rest of the second laser lighttransmitted through the second optical member so as to detect an amountof second laser light.
 3. The optical pickup device according to claim2, wherein the first optical member reflects the first laser lightradiated from the first light source onto the first condensing memberand transmits the second laser light radiated from the second lightsource; and the second optical member reflects some of the second laserlight transmitted through the first optical member onto the secondcondensing member and transmits the rest of the transmitted second laserlight.
 4. The optical pickup device according to claim 3, wherein thelight receiving sensor receives the second laser light transmittedthrough the first and second optical members.
 5. The optical pickupdevice according to claim 4, wherein the first and second condensingmembers are disposed on substantially the same line, and the lightreceiving sensor is disposed along the same line.
 6. The optical pickupdevice according to claim 5, wherein the light receiving sensor isdisposed in a farther position than from the second condensing memberwith respect to the second light source.
 7. The optical pickup deviceaccording to claim 3, further including: a third condensing member thatreflects the rest of the second laser light transmitted through thesecond condensing member into the light receiving sensor, the thirdcondensing member being provided between the second condensing memberand the light receiving sensor.
 8. The optical pickup device accordingto claim 7, wherein the third condensing member has an aperture limitingsurface which limits a light-entrance area of the rest of the secondlaser light transmitted through the second optical member.
 9. Theoptical pickup device according to claim 8, wherein the third condensingmember has the aperture limiting surface formed around a condensingsurface which condenses the rest of the second laser light transmittedthrough the second optical member.
 10. The optical pickup deviceaccording to claim 9, wherein the condensing surface has a convexsurface directed to the second optical member.
 11. The optical pickupdevice according to claim 9, wherein the aperture limiting surface is aplane surface.
 12. The optical pickup device according to claim 7,wherein the direction, where the third condensing member reflects therest of the second laser-light transmitted through the second condensingmember onto the light receiving sensor, is the same as the directionwhere the second optical member reflects some of the second laser ontothe second condensing member.
 13. The optical pickup device according toclaim 3, wherein the first optical member includes a wavelengthselecting film having a property of reflecting the first laser light andtransmitting the second laser light.
 14. The optical pickup deviceaccording to claim 7, wherein when the refractive index of the thirdcondensing member is set to n and the refractive index of a medium withwhich the third condensing member comes in contact is set to n0, anangle θ (θ≦90°) formed between the reflecting surface of the thirdcondensing member and the traveling direction of the light transmittedthrough the second optical member satisfies the following expression 1:θ≦90°−Acrsin(n0/n)  (1).
 15. The optical pickup device according toclaim 1, wherein the second optical member includes: a first surfacethat receives light from the first light source; and a second surfacethat emits the light received from the first surface, a fixing surfacefor fixing the second optical member is formed in the tangentialdirection and the tracking direction, and an angle θb (θb≦90°) formedbetween the second surface and the fixing surface is smaller than anangle θa (θa≦90°) formed between the first surface and the fixingsurface.
 16. An optical disk drive comprising: the optical pickup deviceaccording to claim 1; a base that movably holds the optical pickupdevice; and a rotation driving member that is provided in the base so asto rotationally drive a medium.